{"id":36987,"date":"2024-12-29T01:06:28","date_gmt":"2024-12-28T19:36:28","guid":{"rendered":"https:\/\/samacheerkalvi.guide\/?p=36987"},"modified":"2024-12-30T10:10:20","modified_gmt":"2024-12-30T04:40:20","slug":"samacheer-kalvi-11th-chemistry-guide-chapter-13","status":"publish","type":"post","link":"https:\/\/samacheerkalvi.guide\/samacheer-kalvi-11th-chemistry-guide-chapter-13\/","title":{"rendered":"Samacheer Kalvi 11th Chemistry Guide Chapter 13 Hydrocarbons"},"content":{"rendered":"

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide<\/a> Pdf Chapter 13 Hydrocarbons Text Book Back Questions and Answers, Notes.<\/p>\n

Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 13 Hydrocarbons<\/h2>\n

11th Chemistry Guide Hydrocarbons Text Book Back Questions and Answers<\/h3>\n

Textbook Evaluation:<\/span><\/p>\n

I. Choose the best answer:<\/span><\/p>\n

Question 1.
\nThe correct statement regarding the comparison of staggered and eclipsed conformations of ethane, is
\na) The eclipsed conformation of ethane is more stable than staggered conformation even though the eclipsed conformation has torsional strain.
\nb) The staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.
\nc) The staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain.
\nd) The staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has no torsional strain.
\nAnswer:
\nb) The staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain.<\/p>\n

Question 2.
\nC2<\/sub>H5<\/sub> Br + 2Na \"Samacheer C4<\/sub>H10<\/sub> + 2NaBr.
\nThe above reaction is an example of which of the following
\na) Reimer Tiemann reaction
\nb) Wurtz reaction
\nc) Aldol condensation
\nd) Hoffmann reaction
\nAnswer:
\nb) Wurtz reaction<\/p>\n

Question 3.
\nAn alkyl bromide (A) reacts with sodium in ether to form 4, 5 – diethyloctane, the compound (A) is
\na) CH3<\/sub>(CH2<\/sub>)3<\/sub>Br<\/p>\n

b) CH3<\/sub>(CH2<\/sub>)5<\/sub>Br<\/p>\n

c) CH3<\/sub>(CH2<\/sub>)3<\/sub> CH(Br)CH3<\/sub><\/p>\n

d) \"Samacheer
\nAnswer:
\nd) \"Samacheer<\/p>\n

Question 4.
\nThe C – H bond and C – C bond in ethane are formed by which of the following types of overlap
\na) sp3<\/sup> – s and sp3<\/sup> – sp3<\/sup>
\nb) sp2<\/sup> – s and sp2<\/sup> – sp2<\/sup>
\nc) sp – sp and sp – sp
\nd) p – s and p – p
\nAnswer:
\na) sp3<\/sup> – s and sp3<\/sup> – sp3<\/sup><\/p>\n

Question 5.
\nIn the following reaction,
\n\"Samacheer<\/p>\n

\"Samacheer
\nAnswer:
\nc) \"Samacheer<\/p>\n

\"Samacheer<\/p>\n

Question 6.
\nWhich of the following is optically active
\na) 2 – methyl pentane
\nb) citric acid
\nc) Glycerol
\nd) none of these
\nAnswer:
\na) 2 – methyl pentane<\/p>\n

Question 7.
\nThe compound formed at anode in the electrolysis of an aqueous solution of potassium acetate are
\na) CH4<\/sub> and H2<\/sub>
\nb) CH4<\/sub> and CO2<\/sub>
\nc) C2<\/sub>H6<\/sub> and CO2<\/sub>
\nd) C2<\/sub>H4<\/sub> and Cl2<\/sub>
\nAnswer:
\nc) C2<\/sub>H6<\/sub> and CO2<\/sub><\/p>\n

Question 8.
\nThe general formula for cyclo alkanes
\na) Cn<\/sub>Hn<\/sub>
\nb) Cn<\/sub>H2n<\/sub>
\nC) Cn<\/sub>H2n-2<\/sub>
\nd) Cn<\/sub>H2n + 2<\/sub>
\nAnswer:
\nb) Cn<\/sub>H2n<\/sub><\/p>\n

Question 9.
\nThe compound that will react most readily with gaseous bromine has the formula
\na) C3<\/sub>H6<\/sub>
\nb) C2<\/sub>H2<\/sub>
\nc) C4<\/sub>H10<\/sub>
\nd) C2<\/sub>H4<\/sub>
\nAnswer:
\na) C3<\/sub>H6<\/sub><\/p>\n

Question 10.
\nWhich of the following compounds shall not produce propene by reaction with HBr followed by elimination (or) only direct elimination reaction
\na) \"Samacheer
\nb) CH3<\/sub> – CH2<\/sub> – CH2<\/sub> – OH
\nc) H2<\/sub>C = C = O
\nd) CH3<\/sub> – CH2<\/sub> – CH2<\/sub>Br
\nAnswer:
\nc) H2<\/sub>C = C = O<\/p>\n

\"Samacheer<\/p>\n

Question 11.
\nWhich among the following alkenes on reductive ozonolysis produces only propanone?
\na) 2 – Methyl propene
\nb) 2 – Methyl but – 2 – ene
\nc) 2, 3 – Dimethyl but – 1- ene
\nd) 2, 3 – Dimethyl but – 2 – ene
\nAnswer:
\nd) 2, 3 – Dimethyl but – 2 – ene<\/p>\n

Question 12.
\nThe major product formed when 2 – bromo – 2 – methyl butane is refluxed with ethanolic KOH is
\na) 2 – methylbut – 2- ene
\nb) 2 – methyl butan – 1 – ol
\nc) 2 – methyl but – 1 – ene
\nd) 2 – methyl butan – 2- ol
\nAnswer:
\na) 2 – methylbut – 2- ene<\/p>\n

Question 13.
\nMajor product of the below mentioned reaction is, (CH3<\/sub>)2<\/sub> C = CH2<\/sub> \"Samacheer
\na) 2 – chloro – 1 – iode – 2 – methyl propane
\nb) 1 – chloro – 2 – iodo – 2 – methyl propane
\nc) 1, 2 – dichloro – 2 – methyl propane
\nd) 1, 2 – diiodo – 2 – methyl propane
\nAnswer:
\na) 2 – chloro – 1 – iode – 2 – methyl propane<\/p>\n

Question 14.
\nThe IUPAC name of the following compound is
\n\"Samacheer
\na) trans – 2- chloro – 3- iodo – 2- pentane
\nb) cis – 3- iodo – 4 chloro – 3 – pentane
\nc) trans – 3 – iodo – 4 – chloro – 3 – pentene
\nd) cis – 2 – chloro – 3 iodo – 2 – pentene
\nAnswer:
\na) trans – 2- chloro – 3- iodo – 2- pentane<\/p>\n

Question 15.
\nCis – 2- butene and trans – 2 – butene are
\na) conformational isomers
\nb) structural isomers
\nc) configurational isomers
\nd) optical isomers
\nAnswer:
\nc) configurational isomers<\/p>\n

\"Samacheer<\/p>\n

Question 16.
\nIdentify the compound (A) in the following reaction<\/p>\n

\"Samacheer<\/p>\n

\"Samacheer
\nAnswer:
\na) \"Samacheer<\/p>\n

Question 17.
\n\"Samacheer\"Samacheer CH \u2261 CH , where A is,
\na) Zn
\nb) conc. H2<\/sub>SO4<\/sub>
\nc) alc. KOH
\nd) dil. H2<\/sub>SO4<\/sub>
\nAnswer:
\nc) alc. KOH<\/p>\n

Question 18.
\nConsider the nitration of benzene using mixed con H2<\/sub>SO4<\/sub> and HNO3<\/sub> if a large quantity of KHSO4<\/sub> is added to the mixture, the rate of nitration will be
\na) unchanged
\nb) doubled
\nc) faster
\nd) slower
\nAnswer:
\nd) slower<\/p>\n

Question 19.
\nIn which of the following molecules, all atoms are co-planar
\na) \"Samacheer<\/p>\n

b) \"Samacheer<\/p>\n

c) \"Samacheer
\nd) both (a) and (b)
\nAnswer:
\nd) both (a) and (b)<\/p>\n

Question 20.
\nPropyne on passing through red hot iron tube gives
\na) \"Samacheer<\/p>\n

b) \"Samacheer<\/p>\n

c) \"Samacheer
\nd) none of these
\nAnswer:
\na) \"Samacheer<\/p>\n

\"Samacheer<\/p>\n

Question 21.
\n\"Samacheer is<\/p>\n

a) \"Samacheer<\/p>\n

b) \"Samacheer<\/p>\n

c) both (a) and (b)<\/p>\n

d) \"Samacheer
\nAnswer:
\nd) \"Samacheer<\/p>\n

Question 22.
\nWhich one of the following is non aromatic?
\na) \"Samacheer<\/p>\n

b) \"Samacheer<\/p>\n

c) \"Samacheer<\/p>\n

d) \"Samacheer
\nAnswer:
\nd) \"Samacheer<\/p>\n

Question 23.
\nWhich of the following compounds will not undergo Friedal – crafts reaction easily?
\na) Nitro benzene
\nb) Toluene
\nc) Cumene
\nd) Xylene
\nAnswer:
\na) Nitro benzene<\/p>\n

Question 24.
\nSome meta-directing substituents in aromatic substitution are given. Which one is most deactivating?
\na) – COOH
\nb) – NO2<\/sub>
\nc) -C \u2261 N
\nd) -SO3<\/sub>H
\nAnswer:
\nb) – NO2<\/sub><\/p>\n

Question 25.
\nWhich of the following can be used as the halide component for friedal – crafts reaction?
\na) Chloro benzene
\nb) Bromo benzene
\nc) Chloro ethene
\nd) Isopropyl chloride
\nAnswer:
\nd) Isopropyl chloride<\/p>\n

\"Samacheer<\/p>\n

Question 26.
\nAn alkane isobtainedbydecarboxylation of sodium propionate. Same alkane can be prepared by
\na) Catalytic hydrogenation of propene
\nb) action of sodium metal on iodomethane
\nc) reduction of 1 – chloro propane
\nd) reduction of bromomethane
\nAnswer:
\nb) action of sodium metal on iodomethane<\/p>\n

Question 27.
\nWhich of the following is aliphatic saturated hydrocarbon
\na) C8<\/sub>H18<\/sub>
\nb) C9<\/sub>H18<\/sub>
\nc) C8<\/sub>H14<\/sub>
\nd) All of these
\nAnswer:
\na) C8<\/sub>H18<\/sub><\/p>\n

Question 28.
\nIdentify the compound \u2018Z\u2019 in the following reaction
\n\"Samacheer
\na) Formaldehyde
\nb) Acetaldehyde
\nc) Formic acid
\nd) none of these
\nAnswer:
\na) Formaldehyde<\/p>\n

Question 29.
\nPeroxide effect (Kharasch effect) can be studied in case of
\na) Oct – 4 – ene
\nb) hex – 3 – ene
\nc) pent – 1 – ene
\nd) but – 2 – ene
\nAnswer:
\nc) pent – 1 – ene<\/p>\n

Question 30.
\n2 – butyne on chlorination gives
\na) 1 – chloro butane
\nb) 1, 2 – dichloro butane
\nc) 1, 1, 2, 2 – tetrachlorobutane
\nd) 2, 2, 3, 3 – tetra chloro butane
\nAnswer:
\nd) 2, 2, 3, 3 – tetra chloro butane<\/p>\n

\"Samacheer<\/p>\n

II. Write brief answer to the following questions:<\/span><\/p>\n

Question 31.
\nGive IUPAC names for the following compounds
\n1) CH3<\/sub> – CH = CH – CH = CH – C \u2261 C – CH3<\/sub><\/p>\n

2) \"Samacheer<\/p>\n

3) (CH3<\/sub>)3<\/sub> C – C \u2261 C – CH(CH3<\/sub>)2<\/sub><\/p>\n

4) ethyl isopropyl acetylene<\/p>\n

5) CH \u2261 C – C \u2261 C – C \u2261 CH
\nAnswer:
\n1) \"Samacheer<\/p>\n

2) \"Samacheer<\/p>\n

3) \"Samacheer<\/p>\n

4) ethyl isopropyl acetylene
\n\"Samacheer<\/p>\n

5) \"Samacheer<\/p>\n

Question 32.
\nIdentify the compound A, B, C and D in the following series of reactions
\n\"Samacheer
\nAnswer:
\n\"Samacheer<\/p>\n

Question 33.
\nWrite short notes on ortho, para directors in aromatic electrophilic substitution reactions.
\nAnswer:
\nAll the activating groups are \u2018ortho-para\u2019 directors.
\nExample: – OH, – NH2<\/sub>, -NHR, -NHCOCH3<\/sub>, -OCH3<\/sub> -CH3<\/sub> – C2<\/sub>H5<\/sub> etc.
\nLet us consider the directive influences of phenolic (-OH) group. Phenol is the resonance hybrid of following structures.
\n\"Samacheer<\/p>\n

In these resonance structures, the (-) charge residue is present on ortho and para position of ring structure. It is quite evident that the lone pair of electron on the atom which is attached to the ring involves in resonance and makes the ring more electron rich than benzene. The electron density at ortho and para positions increases as compared to the meta position. Therefore phenolic group activates the benzene ring for electrophilic attack at \u2018ortho\u2019 and \u2018para positions and hence -OH group is an ortho-para director and activator.<\/p>\n

In aryl halides, the strong -I effect of the halogens (electron withdrawing tendency) decreases the electron density of benzene ring, thereby deactivating for electrophilic attack. However the presence of lone pair on halogens involved in the resonance with pi electrons of benzene ring, increases electron density at ortho and para position. Hence the halogen group is an ortho-para director and deactivator.<\/p>\n

\"Samacheer<\/p>\n

Question 34.
\nHow is propyne prepared from an alkene dihalide?
\nAnswer:
\n\"Samacheer<\/p>\n

Question 35.
\nAn alkylhalide with molecular formula C6<\/sub>H13<\/sub>Br on dehydro halogenation gave two isomeric alkenes X and Y with molecular formula C6<\/sub>H12<\/sub>. On reductive ozonolysis, X and Y gave four compounds CH3<\/sub>COCH3<\/sub>, CH3<\/sub>CHO, CH3<\/sub>CH,CHO and (CH3<\/sub>)2<\/sub> CHCHO. Find the alkyihalide.
\nAnswer:
\n\"Samacheer<\/p>\n

Question 36.
\nDescribe the mechanism of Nitration of benzene.
\nAnswer:
\nIt is prepared by the action of a mixture of con. HNO3<\/sub> and con. H2<\/sub>SO4<\/sub> (nitrating mixture) on benzene maintaining the temperature below 333 K.
\nNitration:
\n\"Samacheer<\/p>\n

Sulphuric acid generates the electrophile – NO2<\/sub>+<\/sup>, nitronium ion-from nitric acid. This is an example of aromatic electrophilic substitution reaction.
\n\"Samacheer<\/p>\n

The generation of nitronium ion
\nH2<\/sub>SO4<\/sub> + HONO2<\/sub> \u2192 \"Samacheer + HSO4<\/sub>–<\/sup>
\n\"Samacheer<\/p>\n

To the nitronium ion (being an electron deficient species) the \u03c0 bond of benzene, donates a pair of electrons forming a 6-bond. A species with a + ve charge is formed as an intermediate. This is called ‘arenium ion’ and is stabilised by Resonance.
\n\"Samacheer<\/p>\n

In the last step, the hydrogen atom attached to the carbon carrying the nitro group is pulled out as a proton, by the Lewis base HSO4<\/sub>–<\/sup>, so that stable aromatic system is formed.
\n\"Samacheer<\/p>\n

Question 37.
\nHow does Huckel rule help to decide the aromatic character of a compound.
\nAnswer:
\nIn 1865, August Kekule suggested that benzene consists of a cyclic planar structure of six carbon with alternate single and double bonds.
\nThere were two objections:
\nBenzene forms only one ortho disubstituted products whereas the Kekule\u2019s structure predicts two o-di substituted products as shown below.
\n\"Samacheer<\/p>\n

Kekule\u2019s structure failed to explain why benzene with three double bonds did not give addition reactions like other alkenes.To overcome this objection, Kekule suggested that benzene was mixture of two forms (1 and 2) which are in rapid equilibrium.
\n\"Samacheer<\/p>\n

Resonance description of benzene:
\nThe phenomenon in which two or more structures can be written for a substance which has identical position of atoms is called resonance. The actual structure of the molecule is said to be resonance hybrid of various possible alternative structures. In benzene, Kekule\u2019s structures I & II represented the resonance structure, and structure III is the resonance hybrid of structure I & II.
\nThe structures 1 and 2 exist only in theory. The actual structure of benzene is the hybrid of two hypothetical resonance structures.
\n\"Samacheer<\/p>\n

Spectroscopic measurements:
\nSpectroscopic measurements show that benzene is planar and all of its carbon- carbon bonds are of equal length 1.40 \u00c5. This value lies between carbon-carbon single bond length 1.54 \u00c5 and carbon- carbon double bond length 1.34 \u00c5.<\/p>\n

Molecular orbital structure:
\nThe structure of benzene is best de\u00acscribed in terms of the molecular orbital theory. All the six carbon atoms of benzene are sp2<\/sup> hybridized. Six sp2<\/sup> hybrid orbitals of carbon linearly overlap with six 1 s orbitals of hydrogen atoms to form six C – H sigma bonds. Overlap between the remaining sp2<\/sup> hybrid orbitals of carbon forms six C – C sigma bonds.
\n\"Samacheer
\nFormation of Sigma bond in benzene<\/p>\n

All the \u03c3 bonds in benzene lie in one plane with bond angle 120\u00b0. Each carbon atom in benzene possess an un hybridized p-orbital containing one electron. The lateral overlap of their p-orbital produces 3 \u03c0- bond. The six electrons of the p-orbitals cover all the six carbon atoms and are said to be delocalised. Due to delocalization, strong \u03c0-bond is formed which makes the molecule stable. Hence unlike alkenes and alkynes benzene undergoes substitution reactions rather addition reactions under normal conditions.<\/p>\n

\"Samacheer<\/p>\n

All carbon atoms have the delocalized \u03c0 MO is formed by p-orbitais the overlap of six p-orbitals.<\/p>\n

Representation of benzene:
\nHence, there are three ways in which benzene can be represented.
\n\"Samacheer<\/p>\n

\"Samacheer<\/p>\n

Question 38.
\nSuggest the route for the preparation of the following from benzene.
\n1) 3 – chloro nitrobenzene
\n2) 4 – chlorotoluene
\n3) Bromo benzene
\n4) m – dinitro benzene
\nAnswer:
\n1) 3 – chloro nitrobenzene
\n\"Samacheer<\/p>\n

2) 4 – chlorotoluene
\n\"Samacheer<\/p>\n

3) Bromo benzene
\n\"Samacheer<\/p>\n

4) m – dinitro benzene
\n\"Samacheer<\/p>\n

Question 39.
\nSuggest a simple chemical test to distinguish propane and propene.
\nAnswer:
\nPropene decolourises Br2<\/sub>\/H2<\/sub>O it forms dibromo compound but propane does not react with Br2<\/sub>\/ H2<\/sub>O.<\/p>\n

Question 40.
\nWhat happens when Isobutylene is treated with acidified potassium permanganate?
\nAnswer:
\n\"Samacheer<\/p>\n

Question 41.
\nHow will you convert ethyl chloride into
\n(i) ethane
\n(ii) n – butane
\nAnswer:
\n(i) ethane
\n\"Samacheer<\/p>\n

(ii) n – butane
\n\"Samacheer<\/p>\n

\"Samacheer<\/p>\n

Question 42.
\nDescribe the conformers of n – butane.
\nAnswer:
\nConformations of n-Butane:
\nn-Butane may be considered as a derivative of ethane, as one hydrogen on each carbon is replaced by a methyl group<\/p>\n

Eclipsed conformation:
\nIn this conformation, the distance between the two methyl group is minimum. So there is maximum repulsion between them and it is the least stable conformer.<\/p>\n

Anti or staggered form:
\nIn this conformation, the distance between the two methyl groups is maximum and so there is minimum repulsion between them. And it is the most stable conformer.<\/p>\n

The following potentially energy diagram shows the relative stabilities of various conformers of n-butane.
\n\"Samacheer<\/p>\n

Question 43.
\nWrite the chemical equations for combustion of propane.
\nAnswer:
\nC3<\/sub>H8<\/sub>(g) + 5O2<\/sub>(g) ) \u2192 3CO2<\/sub>(g) + 4H2<\/sub>O(l)
\npropane<\/p>\n

Question 44.
\nExplain Markovnikoff\u2019s rule with suitable example.
\nAnswer:
\nMarkovnikoff \u2018s rule:
\n\u201cWhen an unsymmetrical alkene reacts with hydrogen halide, the hydrogen adds to the carbon that has more number of hydrogen and halogen add to the carbon having fewer hydrogen\u201d. This rule can also be stated as in the addition reaction of alkene\/alkyne, the most electro negative part of the reagent adds on to the least hydrogen attached doubly bonded carbon.<\/p>\n

Addition of water: (Hydration of alkenes)
\nNormally, water does not react with alkenes. In the presence of concentrated sulphuric acid, alkenes react with water to form alcohols. This reaction follows carbocation mechanism and Markovnikoff’s rule.
\n\"Samacheer<\/p>\n

Question 45.
\nWhat happens when ethylene is passed ‘ through cold dilute alkaline potassium permanganate.
\nAnswer:
\nCH2<\/sub> = CH + H2<\/sub>O + (O) \"Samacheer CH2<\/sub>OH – CH2<\/sub>OH
\nEthylene\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Ethylene glycol<\/p>\n

\"Samacheer<\/p>\n

Question 46.
\nWrite the structures of following alkanes.
\n1) 2, 3 – Dimethyl – 6 – (2 – methyl propyl) decane
\n2) 5 – (2 – Ethyl butyl ) – 3, 3, – dimethyldecane
\n3) 5 – (1, 2 – Dimethyl propyl) – 2 – methylnonane
\nAnswer:
\n1) 2, 3 – Dimethyl – 6 – (2 – methyl propyl) decane
\n\"Samacheer<\/p>\n

2) 5 – (2 – Ethyl butyl ) – 3, 3, – dimethyldecane
\n\"Samacheer<\/p>\n

3) 5 – (1, 2 – Dimethyl propyl) – 2 – methylnonane
\n\"Samacheer<\/p>\n

Question 47.
\nHow will you prepare propane from a sodium salt of fatty acid?
\nAnswer:
\n\"Samacheer<\/p>\n

Question 48.
\n\"Samacheer
\nIdentify A and B
\nAnswer:
\nA) \"Samacheer<\/p>\n

b) \"Samacheer<\/p>\n

Question 49.
\nComplete the following :<\/p>\n

i) 2 – butyne\u00a0 \"Samacheer<\/p>\n

ii) CH2<\/sub> = CH2<\/sub> \"Samacheer<\/p>\n

iii) \"Samacheer<\/p>\n

iv) CaC2<\/sub> \"Samacheer
\nAnswer:
\ni) 2 – butyne \"Samacheer
\n\"Samacheer<\/p>\n

ii) CH2<\/sub> = CH2<\/sub> \"Samacheer
\n\"Samacheer<\/p>\n

iii) \"Samacheer
\n\"Samacheer<\/p>\n

iv) CaC2<\/sub> \"Samacheer
\nCaC2<\/sub> + 2H2<\/sub>O \u2192 Ca(OH)2<\/sub> + C2<\/sub>H2<\/sub>\u2191
\nCalcium Carbide\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Acetylene<\/p>\n

Question 50.
\nHow will distinguish 1 – butyne and 2 – butyne?
\nAnswer:
\n\"Samacheer
\n1 – butyne reacts with ammoniacal AgNO3<\/sub> solution it forms white precipitate of silver acetylide but, 2 – butyne doesnot reacts with ammoniacal AgNO3<\/sub> solution.<\/p>\n

\"Samacheer<\/p>\n

11th Chemistry Guide Hydrocarbons Additional Questions and Answers<\/h3>\n

I. Choose the best answer:<\/span><\/p>\n

Question 1.
\nStatement-I: Methane. ethane, prop\u00e8ne, and butane are alkane group compounds.
\nStatement-II: They are obeying C2<\/sub>H2n+2<\/sub> + formula and each member differs from it proceeding member by a CH2<\/sub> group.
\n(a) Statement-I and II are correct and Statement-II is the correct explanation of statement-I.
\n(b) Statement-I and II are correct but statement-II is not the correct explanation of statement-I
\n(e) Stat\u00ebment-I is correct but statement-II is wrong.
\n(d) Statement-I is wrong but statement-II is correct.
\nAnswer:
\n(a) Statement-I and II are correct and Statement-II is the correct explanation of statement-I.<\/p>\n

Question 2.
\nAlkanes are also known as
\na) olefins
\nb) unsaturated aliphatic hydrocarbons
\nc) saturated aromatic hydrocarbon
\nd) paraffin
\nAnswer:
\nd) paraffin<\/p>\n

Question 3.
\nWhich one of the following shows three possible isomeric structures\u2019?
\n(a) C4<\/sub>H10<\/sub>
\n(b) C5<\/sub>H12<\/sub>
\n(c) C6<\/sub>H12<\/sub>
\n(d) C3<\/sub>H4<\/sub>
\nAnswer:
\n(b) C5<\/sub>H12<\/sub><\/p>\n

Question 4.
\nThe gas supplied in cylinders for cooking is
\na) marsh gas
\nb) LPG
\nc) mixture CH4<\/sub> and C2<\/sub>H6<\/sub>
\nd) mixture of ethane and propane
\nAnswer:
\nd) mixture of ethane and propane<\/p>\n

Question 5.
\nWhich of the following compound cannot be prepared by Kolbe\u2019s electrolytic method\u2019?
\n(a) CH3<\/sub>-CH3<\/sub>
\n(b) CH4<\/sub>
\n(c) CH2<\/sub> = CH2<\/sub>
\n(d) CH = CH
\nAnswer:
\n(b) CH4<\/sub><\/p>\n

\"Samacheer<\/p>\n

Question 6.
\nSoda-lime is
\na) NaOH
\nb) NaOH + CaO
\nc) CaO
\nd) Na2<\/sub>CO3<\/sub>
\nAnswer:
\nb) NaOH + CaO<\/p>\n

Question 7.
\nStatement – I : Alkenes shows both structural and geometrical isomerism.
\nStatement – II : Because of the presence of double bond.
\n(a) Statement – I and II are correct and statement-II is correct explanation of statement – I.
\n(b) Statement – I and II are correct but statement-II is not correct explanation of statement – I
\n(c) Statement – I is correct but statement – II is wrong.
\n(d) Statement – II is wrong but statement – II is correct.
\nAnswer:
\n(a) Statement – I and II are correct and statement – II is correct explanation of statement – I.<\/p>\n

Question 8.
\nHydrocarbon which is liquid at room temperature is
\na) Pentane
\nb) Butane
\nc) Propane
\nd) Ethane
\nAnswer:
\na) Pentane<\/p>\n

Question 9.
\nPyrolysis of Methane and respectively are
\na) Exothermic & Endothermic
\nb) Endothermic & Exothermic
\nc) Both are endothermic
\nd) Both are exothermic
\nAnswer:
\nc) Both are endothermic<\/p>\n

Question 10.
\nPeroxide effect is not observed in ………..
\n(a) HCl
\n(b) HI
\n(c) HBr
\n(d) Both (a) and (b)
\nAnswer:
\n(d) Both (a) and (b)<\/p>\n

\"Samacheer<\/p>\n

Question 11.
\nFinal products of complete oxidation of hydrocarbon is
\na) Acid
\nb) Dihydric alcohol
\nc) Aldehyde
\nd) H2<\/sub>O + CO2<\/sub>
\nAnswer:
\nd) H2<\/sub>O + CO2<\/sub><\/p>\n

Question 12.
\nIsomerisation in alkane can be brought by using
\na) Al2<\/sub>O3<\/sub>
\nb) Fe2<\/sub>O3<\/sub>
\nc) Anh.AlCl3<\/sub>\/ HCl at 200\u00b0C
\nd) Cone. H2<\/sub>SO4<\/sub>
\nAnswer:
\nc) Anh.AlCl3<\/sub>\/ HCl at 200\u00b0C<\/p>\n

Question 13.
\nIn aromatization of n – hexane, the catalyst used is
\na) Cr2<\/sub>O3<\/sub>
\nb) V2<\/sub>O5<\/sub>
\nc) Mo2<\/sub>O3<\/sub>
\nd) All
\nAnswer:
\nd) All<\/p>\n

Question 14.
\nThe most oxidized form of ethane is
\na) CO2<\/sub>
\nb) HCHO
\nc) HCOOH
\nd) CH3<\/sub>COOH
\nAnswer:
\na) CO2<\/sub><\/p>\n

Question 15.
\nThe following substance is used as anti-knocking compound
\na) TEL
\nb) Lead tetrachloride
\nc) Lead acetate
\nd) C2<\/sub>H2<\/sub>PbCl
\nAnswer:
\na) TEL<\/p>\n

\"Samacheer<\/p>\n

Question 16.
\nThe molecular formula of benzene is ………….
\n(a) C6<\/sub>H6<\/sub>
\n(b) C6<\/sub>H5<\/sub>
\n(c) C7<\/sub>H8<\/sub>
\n(d) CH4<\/sub>
\nAnswer:
\n(a) C6<\/sub>H6<\/sub><\/p>\n

Question 17.
\nThe most stable conformation of ethane is
\na) Eclipsed
\nb) Skew
\nc) Staggered
\nd) All are equally stable
\nAnswer:
\nc) Staggered<\/p>\n

Question 18.
\nIUPAC name of the following compound
\n\"Samacheer
\na) 3 – methyl hexane
\nb) 3 – Ethyl pentane
\nc) 2, 3 – dimethyl pentane
\nd) 2, 2 – dimethyl pentane
\nAnswer:
\na) 3 – methyl hexane<\/p>\n

Question 19.
\nThe number of sigma bonds formed in ethane by the overlapping of sp3 – sp3 orbitals
\na) 7
\nb) 5
\nc) 1
\nd) 4
\nAnswer:
\nc) 1<\/p>\n

Question 20.
\nWhich one of the following is not an ortho-para director?
\n(a) – NO2<\/sub>
\n(b) – CH3<\/sub>
\n(c) – OH
\n(d) – C2<\/sub>H5<\/sub>
\nAnswer:
\n(a) – NO2<\/sub><\/p>\n

\"Samacheer<\/p>\n

Question 21.
\nThe correct IUPAC name of the following alkane is
\n\"Samacheer
\na) 3, 6 – diethyl – 2- methyloctane
\nb) 5 – isopropyl – 3- ethyloctane
\nc) 3 – ethyl – 5- isopropyloctane
\nd) 3 – isopropyl – 6 – ethyloctane
\nAnswer:
\na) 3, 6 – diethyl – 2- methyloctane<\/p>\n

Question 22.
\nIn the Wurtz reaction, n-hexane is obtained from
\na) n – propyl chloride
\nb) n – butyl chloride
\nc) Ethyl chloride
\nd) isopropyl chloride
\nAnswer:
\na) n – propyl chloride<\/p>\n

Question 23.
\nWhen sodium acetate is heated with soda lime the reaction is called
\na) Dehydration
\nb) Decarboxylation
\nc) Dehydrogenation
\nd) Dehydrohalogenation
\nAnswer:
\nb) Decarboxylation<\/p>\n

Question 24.
\nThe following substance reacts with water to give ethane
\na) CH4<\/sub>
\nb) C2<\/sub>H5<\/sub>MgBr
\nc) C2<\/sub>H4<\/sub>OH
\nd) C2<\/sub>H5<\/sub>OC2<\/sub>H5<\/sub>
\nAnswer:
\nb) C2<\/sub>H5<\/sub>MgBr<\/p>\n

Question 25.
\nReaction of ROH with R’ MgX produces
\na) RH
\nb) R’H
\nc) R – R
\nd) R’ – R”
\nAnswer:
\nb) R’H<\/p>\n

\"Samacheer<\/p>\n

Question 26.
\nThe solvent used in Wurtz reacton is
\na) C2<\/sub>H5<\/sub>OH(aq)
\nb) CH3<\/sub>COOH
\nc) H2<\/sub>O
\nd) C2<\/sub>H5<\/sub>OC2<\/sub>H5<\/sub>(dry)
\nAnswer:
\nd) C2<\/sub>H5<\/sub>OC2<\/sub>H5<\/sub>(dry)<\/p>\n

Question 27.
\nWhich of the following is less reactive than benzene towards electrophilic substitution reactions?
\n(a) Nitrobenzene
\n(b) Aniline
\n(c) Bromobenzene
\n(d) Chlorobenzene
\nAnswer:
\n(a) Nitrobenzene<\/p>\n

Question 28.
\nThe compound with the highest boiling point is
\na) n-Hexane
\nb) n – Pentane
\nc) 2, 2 – dimethyl propane
\nd) 2 – methyl butane
\nAnswer:
\na) n-Hexane<\/p>\n

Question 29.
\nThe increasing order of reduction of alkyl halides with zinc and dilute HCl is
\na) R – Cl < R – I < R – Br
\nb) R – Cl < R – Br < R – I
\nc) R – I < R – Br < R – Cl
\nd) R – Br < R – I < R – Cl
\nAnswer:
\nb) R – Cl < R – Br < R – I<\/p>\n

Question 30.
\nThe volume of oxygen required for the complete combustion of 4 lit of ethane is
\na) 4 lit
\nb) 8 lit
\nc) 12 lit
\nd) 14 lit
\nAnswer:
\nd) 14 lit<\/p>\n

\"Samacheer<\/p>\n

Question 31.
\nThe dihedral angle between the hydrogen atoms of 2 methyl groups in the staggered conformation of ethane is
\na) 0\u00b0
\nb) 60\u00b0
\nc) 120\u00b0
\nd) 240\u00b0
\nAnswer:
\nb) 60\u00b0<\/p>\n

Question 32.
\nThe distances between the hydrogen nuclei in staggered and eclipsed form in ethane respectively are
\na) 2.55 \u00c5 & 2.29 \u00c5
\nb) 1.54 \u00c5 & 1.34 \u00c5
\nc) 3.5 \u00c5 & 2.5 \u00c5
\nd) 2.29 \u00c5 & 2.55 \u00c5
\nAnswer:
\na) 2.55 \u00c5 & 2.29 \u00c5<\/p>\n

Question 33.
\nEnergy barrier between staggered and eclipsed form in ethane is
\na) 0.6 kcal \/ mole
\nb) 2.9 kcal \/ mole
\nc) 12 kcal \/ mole
\nd) 14 cal \/ mole
\nAnswer:
\nb) 2.9 kcal \/ mole<\/p>\n

Question 34.
\nIUPAC name of the following compound
\n\"Samacheer
\na) 3 – Ethyl, 5 – methyl heptane
\nb) 5 – Ethyl, 3 – methyl heptane
\nc) 2 – Ethyl, 5 – methyl heptane
\nd) 4 – Ethyl, 5 – methyl heptane
\nAnswer:
\na) 3 – Ethyl, 5 – methyl heptane<\/p>\n

Question 35.
\nEthylene is converted to ethane in the presence of Ni at 300\u00b0C. In this reaction the hybridization of carbon changes from
\na) sp to sp2<\/sup>
\nb) sp2<\/sup> to sp3<\/sup>
\nc) sp3<\/sup> to sp
\nd) sp to sp3<\/sup>
\nAnswer:
\nb) sp2<\/sup> to sp3<\/sup><\/p>\n

\"Samacheer<\/p>\n

Question 36.
\nIn which of the following reactions in the preparation of ethane a new C – C bond is formed
\na) Sabatier – Senderen\u2019s reaction
\nb) Reduction of ethyl iodide
\nc) Decarboxylation
\nd) Kolbe\u2019s electrolysis
\nAnswer:
\nd) Kolbe\u2019s electrolysis<\/p>\n

Question 37.
\nSelect the correct statements
\na) eclipsed and staggered ethanes give different products on reaction with chlorine in presence of light
\nb) the conformational isomers can be isolated at room temperature
\nc) torsional strain is minimum in ethane at dihedral angles 60\u00b0, 180\u00b0 and 300\u00b0
\nd) steric strain is minimum in gauche form of n – butane
\nAnswer:
\nc) torsional strain is minimum in ethane at dihedral angles 60\u00b0, 180\u00b0 and 300\u00b0<\/p>\n

Question 38.
\nThe fully eclipsed conformation of n-butane is least stable due to the presence of
\na) bond opposition strain only
\nb) steric strain only
\nc) bond opposition strain as well as steric strain
\nd) no strain is present in the molecule
\nAnswer:
\nc) bond opposition strain as well as steric strain<\/p>\n

Question 39.
\nVinyl group among the following is
\na) (CH3<\/sub>)2<\/sub> CH –
\nb) HC \u2261 C –
\nc) H2<\/sub>C = CH – CH2<\/sub> –
\nd) CH2<\/sub> = CH –
\nAnswer:
\nd) CH2<\/sub> = CH –<\/p>\n

Question 40.
\nThe alkene that exhibits geometrical isomerism is
\na) propene
\nb) 2 – methyl propene
\nc) 2 – butene
\nd) 2 – methyl – 2 – butene
\nAnswer:
\nc) 2 – butene<\/p>\n

\"Samacheer<\/p>\n

Question 41.
\n\"Samacheer
\na) 5 – methylocta – 1, 3, 5, 7 – tetraene
\nb) 4 – methylocta – 1, 3, 5, 7 – tetraene
\nc) 4 – butenylocta -1, 3- diene
\nd) octa – 1, 5 – diene
\nAnswer:
\nb) 4 – methylocta – 1, 3, 5, 7 – tetraene<\/p>\n

Question 42.
\nCH2<\/sub> = C (CH2<\/sub>CH2<\/sub>CH3<\/sub>)2<\/sub>
\na) 2 – Propyl pent – 1 – ene
\nb) 2 – Propyl pent – 2- ene
\nc) 2 – Propyl pent – 3 – ene
\nd) 3 – Propyl pent – 1- ene
\nAnswer:
\na) 2 – Propyl pent – 1 – ene<\/p>\n

Question 43.
\nThe number of sigma (\u03c3) and pi (\u03c0) bonds in the following structure are
\na) \u03c3 bonds – 33 \u03c0 bonds – 2
\nb) \u03c3 bonds – 22 \u03c0 bonds – 2
\nc) \u03c3 bonds – 42 \u03c0 bonds – 2
\nd) \u03c3 bonds – 40 \u03c0 bonds – 3
\nAnswer:
\na) \u03c3 bonds – 33 \u03c0 bonds – 2<\/p>\n

Question 44.
\nIn dehydrohalogenation, hydrogen and halogen are removed from
\na) the same carbon atom
\nb) from adjacent carbon atoms
\nc) from isolate carbon atoms
\nd) from any two carbon atoms
\nAnswer:
\nb) from adjacent carbon atoms<\/p>\n

Question 45.
\nEthylene readily undergoes the following type of reaction.
\na) Elimination
\nb) Addition
\nc) Rearrangement
\nd) Substitution
\nAnswer:
\nb) Addition<\/p>\n

\"Samacheer<\/p>\n

Question 46.
\nBaeyer\u2019s reagent is
\na) Aqueous bromine solution
\nb) Neutral permanganate solution
\nc) Acidified permanganate solution
\nd) Alkaline potassium permanganate solution
\nAnswer:
\nd) Alkaline potassium permanganate solution<\/p>\n

Question 47.
\nBaeyer\u2019s reagent oxidizes ethylene to
\na) Ethylene chlorohydrin
\nb) Ethyl alcohol
\nc) CO2<\/sub> and H2<\/sub>O
\nd) Ethane – 1, 2 – diol
\nAnswer:
\nd) Ethane – 1, 2 – diol<\/p>\n

Question 48.
\nOn reductive ozonolysis ethylene gives
\na) Aldehyde
\nb) Ketone
\nc) Carboxylic acid
\nd) Ether
\nAnswer:
\na) Aldehyde<\/p>\n

Question 49.
\nPolythene is obtained by the polymerization of
\na) Styrene
\nb) A mixture of ethylene and styrene
\nc) Acetylene
\nd) Ethene
\nAnswer:
\nc) Acetylene<\/p>\n

Question 50.
\nPolytetrafluoroethylene is commercially known as
\na) Teflon
\nb) Freon
\nc) Lewisite
\nd) Westron
\nAnswer:
\na) Teflon<\/p>\n

\"Samacheer<\/p>\n

Question 51.
\nPolythens is
\na) (- H2<\/sub>C = CH2<\/sub> -)n<\/sub>
\nb) (- HC = CH – )n<\/sub>
\nc) (- H3<\/sub>C – CH3<\/sub> – )n<\/sub>
\nd) (- H2<\/sub>C – CH2<\/sub> -)n<\/sub>
\nAnswer:
\nd) (- H2<\/sub>C – CH2<\/sub> -)n<\/sub><\/p>\n

Question 52.
\nWhen ethanol vapours are passed over alumina heated at 350\u00b0C, the main product obtained is
\na) C2<\/sub>H6<\/sub>
\nb) C2<\/sub>H4<\/sub>
\nc) C2<\/sub>H2<\/sub>
\nd) C2<\/sub>H5<\/sub>OC2<\/sub>H5<\/sub>
\nAnswer:
\nb) C2<\/sub>H4<\/sub><\/p>\n

Question 53.
\nDehydrohalogenation of ethyl chloride in presence of ale. KOH produces the following
\na) HC \u2261 CH + KCl + H2<\/sub>O
\nb) CH4<\/sub> + KCl + H2<\/sub>O
\nc) CH2<\/sub> = CH2<\/sub> + KCl + H2<\/sub>O
\nd) C2<\/sub>H4<\/sub> + HCl
\nAnswer:
\nc) CH2<\/sub> = CH2<\/sub> + KCl + H2<\/sub>O<\/p>\n

Question 54.
\nEthylene is prepared by
\na) Dehalogenation of chloroform
\nb) Pyrolysis of ethane at 450\u00b0C
\nc) Dehydration of methanol with Al2<\/sub>O3<\/sub> \/ 350\u00b0C
\nd) Methyl chloride on reduction
\nAnswer:
\nb) Pyrolysis of ethane at 450\u00b0C<\/p>\n

Question 55.
\nThe peroxide effect involves
\na) Ionic mechanism
\nb) Free – radical mechanism
\nc) Heterolytic fission of double bond
\nd) Homolytic fission of double bond
\nAnswer:
\nb) Free – radical mechanism<\/p>\n

\"Samacheer<\/p>\n

Question 56.
\nIn which of the following will Kharasch effect operate?
\na) CH3<\/sub> – CH2<\/sub> – CH = CH2<\/sub> + HCl
\nb) CH3<\/sub> – CH2<\/sub> – CH = CH2<\/sub> + HBr
\nc) CH3<\/sub> – CH = CH – CH3<\/sub> + HBr
\nd) CH3<\/sub> – CH2<\/sub> – CH = CH2<\/sub> + HI
\nAnswer:
\nb) CH3<\/sub> – CH2<\/sub> – CH = CH2<\/sub> + HBr<\/p>\n

Question 57.
\nAnti Markownikoff addition of HBr is not observed in
\na) Propene
\nb) Butene – 1
\nc) Butene – 2
\nd) pentene – 2
\nAnswer:
\nc) Butene – 2<\/p>\n

Question 58.
\nConditions used for the formation of ethylene glycol from ethylene
\na) bromine water
\nb) cold alkaline KMnO4<\/sub>
\nc) dil H2<\/sub>SO4<\/sub>, 60\u00b0C
\nd) Ag \/ 200\u00b0C
\nAnswer:
\nb) cold alkaline KMnO4<\/sub><\/p>\n

Question 59.
\nThe olefin which on ozonolysis gives CH3<\/sub>CH2<\/sub>CHO and CH3<\/sub>CHO is
\na) 1 – butene
\nb) 2 – butene
\nc) 1 – pentene
\nd) 2 – pentene
\nAnswer:
\nd) 2 – pentene<\/p>\n

Question 60.
\nIn the following reaction, A and B respectively are,
\n\"Samacheer
\na) C2<\/sub>H4<\/sub> and alcoholic KOH \/ \u2206
\nb) C2<\/sub>H5<\/sub>Cl and aqueous KOH \/ \u2206
\nc) C2<\/sub>H5<\/sub>OH and aq KOH \/ \u2206
\nd) C2<\/sub>H2<\/sub> and Br2<\/sub>
\nAnswer:
\na) C2<\/sub>H4<\/sub> and alcoholic KOH \/ \u2206<\/p>\n

\"Samacheer<\/p>\n

Question 61.
\nThe number of possible alkynes with molecular formula C5<\/sub>H8<\/sub> is
\na) 3
\nb) 4
\nc) 5
\nd) 6
\nAnswer:
\na) 3<\/p>\n

Question 62.
\nThe number of open chain structural isomers possible with molecular formula C5H8 is
\na) 7
\nb) 6
\nc) 5
\nd) 4
\nAnswer:
\na) 7<\/p>\n

Question 63.
\nAlkynes exhibit.
\na) Chain isomerism
\nb) Position isomerism
\nc) Functional isomerism
\nd) All the above
\nAnswer:
\nd) All the above<\/p>\n

Question 64.
\nThe IUPAC name of the compound having the formula CH \u2261 C – CH = CH2<\/sub>
\na) Butene – 2 – ye
\nb) But – 2- yne – 3 – ene
\nc) 3 – butane 1 – ene
\nd) But – 1 – ene – 3 – yne
\nAnswer:
\nd) But – 1 – ene – 3 – yne<\/p>\n

Question 65.
\nAcetylene can be obtained by the electrolysis of the following compound
\na) Potassium fumerate
\nb) Potassium succinate
\nc) Potassium acetate
\nd) Potassium formate
\nAnswer:
\na) Potassium fumerate<\/p>\n

\"Samacheer<\/p>\n

Question 66.
\nThe gas obtained when ethylene chloride reacts with alcoholic potash and sodamide is
\na) C2<\/sub>H4<\/sub>
\nb) C2<\/sub>H6<\/sub>
\nc) C2<\/sub>H2<\/sub>
\nd) C2<\/sub>H5<\/sub>Cl
\nAnswer:
\nc) C2<\/sub>H2<\/sub><\/p>\n

Question 67.
\nPVC is the polymer of the following
\na) Ethyl chloride
\nb) Vinyl Chloride
\nc) Allyl Chloride
\nd) Ethynyl chloride
\nAnswer:
\nb) Vinyl Chloride<\/p>\n

Question 68.
\nWhich of the following possess acidic hydrogen
\na) C2<\/sub>H6<\/sub>
\nb) C2<\/sub>H4<\/sub>
\nc) C2<\/sub>H2<\/sub>
\nd) CH4<\/sub>
\nAnswer:
\nc) C2<\/sub>H2<\/sub><\/p>\n

Question 69.
\nHydrocarbon which gives an oxyacetylene flame
\na) ethane
\nb) ethene
\nc) ethyne
\nd) ethanol
\nAnswer:
\nc) ethyne<\/p>\n

Question 70.
\nThe isomer of propyne
\na) Allene
\nb) Propene
\nc) Cyclopropane
\nd) Propane
\nAnswer:
\na) Allene<\/p>\n

\"Samacheer<\/p>\n

Question 71.
\nBond angle between C – C in alkyne
\na) 109\u00b0.28′
\nb) 120\u00b0
\nc) 180\u00b0
\nd) 60\u00b0
\nAnswer:
\nc) 180\u00b0<\/p>\n

Question 72.
\nThe molecule having linear structure is
\na) Methane
\nb) Ethylene
\nc) Acetylene
\nd) Water
\nAnswer:
\nc) Acetylene<\/p>\n

Question 73.
\nThe C – C bond length is shortest in
\na) C2<\/sub>H6<\/sub>
\nb) C3<\/sub>H8<\/sub>
\nc) C6<\/sub>H6<\/sub>
\nd) C2<\/sub>H4<\/sub>
\nAnswer:
\nb) C3<\/sub>H8<\/sub><\/p>\n

Question 74.
\nThe hydrolysis of Mg2<\/sub>C3<\/sub> produces
\na) acetylene
\nb) propyne
\nc) butyne
\nd) ethylene
\nAnswer:
\nb) propyne<\/p>\n

Question 75.
\n1 – pentyne and 2 – pentyne can be distinguished by
\na) Silver mirror test
\nb) Iodoform test
\nc) Addition of H2<\/sub>
\nd) Baeyers test
\nAnswer:
\na) Silver mirror test<\/p>\n

\"Samacheer<\/p>\n

Question 76.
\nAcetylene on reaction with silver nitrate shows
\na) Oxidizing property
\nb) Reducing property
\nc) Basic nature
\nd) Acidic nature
\nAnswer:
\nd) Acidic nature<\/p>\n

Question 77.
\nThe acidic nature of hydrogens in acetylene cannot be explained by the reaction with
\na) Sodium metal
\nb) Ammonical cuprous chloride solution
\nc) Ammonical silver nitrate solution
\nd) HCN
\nAnswer:
\nd) HCN<\/p>\n

Question 78.
\nWestron is the solvent obtained by the reaction of chlorine with
\na) Ethylene
\nb) Ethyne
\nc) Ethane
\nd) Methane
\nAnswer:
\nb) Ethyne<\/p>\n

Question 79.
\nCH \u2261 CH\"Samacheer is
\na) CH2<\/sub> = CH – CH = CH2<\/sub>
\nb) HC \u2261 C – CH3<\/sub>
\nc) CH2<\/sub> = CH – CH3<\/sub>
\nd) CH3<\/sub> – CH2<\/sub> – CH3<\/sub>
\nAnswer:
\nb) HC \u2261 C – CH3<\/sub><\/p>\n

Question 80.
\nHydration of ethyne to ethanal takes place through the formation of
\na) CH3<\/sub>CH(OH)2<\/sub>
\nb) CH2<\/sub> = CHOH
\nc) CH2<\/sub> = CHO–<\/sup>
\nd) CH \u2261 C–<\/sup>
\nAnswer:
\nb) CH2<\/sub> = CHOH<\/p>\n

\"Samacheer<\/p>\n

Question 81.
\n\"Samacheer B is
\na) Acetylene
\nb) Acetaldehyde
\nc) Acetone
\nd) Acetic acid
\nAnswer:
\nb) Acetaldehyde<\/p>\n

Question 82.
\n\"Samacheer is
\na) Ethyl chloride
\nb) 1, 2 dichloro ethene
\nc) Vinyl chloride
\nd) Ethylidine chloride
\nAnswer:
\nc) Vinyl chloride<\/p>\n

Question 83.
\n\"Samacheer The Polymer ‘B’ is
\na) orlon
\nb) PVC
\nc) nylon
\nd) Teflon
\nAnswer:
\nb) PVC<\/p>\n

Question 84.
\nBenzene is ______ molecule.
\na) Tetrahedral
\nb) Planar
\nc) Trigonal
\nd) Square planar
\nAnswer:
\nb) Planar<\/p>\n

Question 85.
\nBond length of C – C in benzene.
\na) 1.34 \u00c5
\nb) 1.39 \u00c5
\nc) 1.54 \u00c5
\nd) 1.20 \u00c5
\nAnswer:
\nc) 1.54 \u00c5<\/p>\n

\"Samacheer<\/p>\n

Question 86.
\nThe resonance energy Benzene is
\na) 36 kcal \/ mol
\nb) 85.8 kJ \/ mole
\nc) 150.48 kJ \/ mole
\nd) Both (a) and (c)
\nAnswer:
\nd) Both (a) and (c)<\/p>\n

Question 87.
\nIn Huckel\u2019s (4n + 2) \u03c0 rule for aromaticity, \u2018n\u2019 represents
\na) Number of carbon atoms
\nb) Number of rings
\nc) Whole number
\nd) Fractional number (or) integer (or) zero
\nAnswer:
\nc) Whole number<\/p>\n

Question 88.
\nCoal tar is obtained as a by product during
\na) Destructive distillation of wood
\nb) Destructive distillation of coal
\nc) Destructive distillation of bones
\nd) steam distillation of light oil
\nAnswer:
\nb) Destructive distillation of coal<\/p>\n

Question 89.
\nGammaxene is ________ isomer of benzene hexa chloride.
\na) \u03b1
\nb) \u03b2
\nc) \u03b3
\nd) \u03b4
\nAnswer:
\nc) \u03b3<\/p>\n

Question 90.
\nThe empirical formula of benzene and acetylene is\/are
\na) CH2<\/sub>, CH
\nb) CH2<\/sub>, CH2<\/sub>
\nc) CH, CH
\nd) CH3<\/sub>, CH3<\/sub>
\nAnswer:
\nc) CH, CH<\/p>\n

\"Samacheer<\/p>\n

Question 91.
\nChemical name of the insecticide gammaxene is
\na) DDT
\nb) Benzene hexa chloride
\nc) Chloral
\nd) Hexa chloro ethane
\nAnswer:
\nb) Benzene hexa chloride<\/p>\n

Question 92.
\nWhich is non benzenoidal aromatic compound?
\na) Benzene
\nb) Pyridine
\nc) Toluene
\nd) Phenol
\nAnswer:
\nb) Pyridine<\/p>\n

Question 93.
\nBenzene is purified by
\na) distillation
\nb) fractional distillation
\nc) Evaporation
\nd) sublimation
\nAnswer:
\nb) fractional distillation<\/p>\n

Question 94.
\nPreparation of benzene from phenol is
\na) Reduction
\nb) Oxidation
\nc) Addition
\nd) Dehydrogenation
\nAnswer:
\na) Reduction<\/p>\n

Question 95.
\nThe true statement about benzene is
\na) Because of unsaturation benzene easily undergoes addition reactions
\nb) There are two types C – C bonds in benzene molecule
\nc) There is a cyclic delocalization of pi – electrons in benzene
\nd) Mono substitution of benzene gives three isomeric products
\nAnswer:
\nc) There is a cyclic delocalization of pi – electrons in benzene<\/p>\n

\"Samacheer<\/p>\n

Question 96.
\n– COOH group in electrophilic substitution directs the incoming group to
\na) o – position
\nb) p – position
\nc) m – position
\nd) o – and p – position
\nAnswer:
\nc) m – position<\/p>\n

Question 97.
\nWhich of the following is not meta directing group?
\na) -SO3<\/sub>H
\nb) – NO2<\/sub>
\nc) – CN
\nd) – NH2<\/sub>
\nAnswer:
\nd) – NH2<\/sub><\/p>\n

Question 98.
\nWhich among the following is very strong o – , p – directing group?
\na) – Cl
\nb) – OR
\nc) – NH2<\/sub>
\nd) – NHR
\nAnswer:
\nd) – NHR<\/p>\n

Question 99.
\nCyclo butadiene is said to be
\na) Aromatic
\nb) Aliphatic
\nc) anti aromatic
\nd) heterocyclic
\nAnswer:
\nc) anti aromatic<\/p>\n

Question 100.
\nIn the reaction \"Samacheer
\nthe attacking species is
\na) Cl2<\/sub>
\nb) Cl+<\/sup>
\nc) Cl–<\/sup>
\nd) FeCl4<\/sub>–<\/sup>
\nAnswer:
\nb) Cl+<\/sup><\/p>\n

\"Samacheer<\/p>\n

Question 101.
\nThe electrophile in Acetylation of Benzene
\n\"Samacheer
\nAnswer:
\nb) \"Samacheer<\/p>\n

Question 102.
\nThe ratio of sigma and pi bonds in benzene is
\na) 4 : 1
\nb) 2 : 3
\nc) 6 : 1
\nd) 1 : 1
\nAnswer:
\na) 4 : 1<\/p>\n

Question 103.
\nBenzene reacts with _______ to yield acetophenone.
\na) CH3<\/sub>COCl + AlCl3<\/sub>
\nb) C6<\/sub>H5<\/sub>COCl + AlCl3<\/sub>
\nc) RCOCl + AlCl3<\/sub>
\nd) C2<\/sub>H5<\/sub>COCl + AlCl3<\/sub>
\nAnswer:
\na) CH3<\/sub>COCl + AlCl3<\/sub><\/p>\n

Question 104.
\nThe order of activites of the various O and P director is
\na) – O–<\/sup> > – OH > – OCOCH3<\/sub> > – COCH3<\/sub>
\nb) – OH > – O–<\/sup> > – OCOCH3<\/sub> > – COCH3<\/sub>
\nc) – OH > – O–<\/sup> > – COCH3<\/sub> > – OCOCH3<\/sub>
\nd) -O–<\/sup> > – COCH3<\/sub> > -OCOCH3<\/sub> > -OH
\nAnswer:
\na) – O–<\/sup> > – OH > – OCOCH3<\/sub> > – COCH3<\/sub><\/p>\n

\"Samacheer<\/p>\n

II. Very short question and answers (2 Marks):<\/span><\/p>\n

Question 1.
\nWhat are alkanes? Give example.
\nAnswer:
\nAlkanes are saturated hydrocarbons represented by the general formula Cn<\/sub>H2n + 2<\/sub> where \u2018n\u2019 is the number of carbon atoms in the molecule. Methane CH4<\/sub>, is- the first member of alkane family. The successive members are ethane C2<\/sub>H6<\/sub>, propane C3<\/sub>H8<\/sub>,butane C4<\/sub>H10<\/sub>, pentane C5<\/sub>H12<\/sub> and so on. It is evident that each member differs from its proceeding or succeeding member by a -CH2<\/sub> group.<\/p>\n

Question 2.
\nGive the IUPAC name of the following alkane.
\na) \"Samacheer<\/p>\n

b) \"Samacheer
\nAnswer:
\na) \"Samacheer<\/p>\n

b) \"eer<\/p>\n

Question 3.
\nDraw the structural formula for 4,5 – diethyl – 3, 4, 5 – trimethyl octane.
\nAnswer:
\n\"Samacheer<\/p>\n

Question 4.
\nHow is methane prepared from sodium acetate?
\nAnswer:
\nWhen a mixture of sodium salt of carboxylic acid and soda lime (sodium hydroxide + calcium oxide) is heated, alkane is formed. The alkane formed has one carbon atom less than carboxylic acid. This process of eliminating carboxylic
\ngroup is known as decarboxylation.
\nCH3<\/sub>COONa + NaOH \"Samacheer CH4<\/sub> + Na2<\/sub>CO3<\/sub>
\nSodium acetate\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Methane<\/p>\n

\"Samacheer<\/p>\n

Question 5.
\nWrite a short note on Kolbe\u2019s Electrolytic method.
\nAnswer:
\nWhen sodium or potassium salt of carboxylic acid is electrolyzed, a higher alkane is formed. The decarboxylative dimerization of two carboxylic acid occurs. This method is suitable for preparing symmetrical alkanes(R-R).
\n\"Samacheer<\/p>\n

Question 6.
\nHow will you convert chloro propane into propane?
\nAnswer:
\nWhen chloro propane is reduced with Zn \/ HCl it gives propane.
\nExample:
\n\"Samacheer<\/p>\n

Question 7.
\nExplain the combustion reaction of alkane with suitable example.
\nAnswer:
\nA combustion reaction is a chemical reaction between a substances and oxygen with evolution of heat and light (usually as a flame). In the presence of sufficient oxygen, alkanes undergoes combustion when ignited and produces carbondioxide and water.<\/p>\n

The combustion reaction is expressed as follows.
\nExample:
\nCH4<\/sub> + 2O2<\/sub> \u2192 CO2<\/sub> + 2H2<\/sub>O
\n\u2206H\u00b0 = -890.4 KJ<\/p>\n

When alkanes burn in insufficient supply of oxygen, they form carbonmonoxide and carbon black.
\n2CH4<\/sub> + 3O2<\/sub> \"Samacheer 2CO + 4H2<\/sub>O
\nCH4<\/sub> + O2<\/sub> \u2192 C + 2H2<\/sub>O<\/p>\n

Question 8.
\nHow are the following compound prepared by the Aromatisation method?
\n(i) Benzene
\n(ii) Toluene
\nAnswer:
\n(i) Benzene
\nn-Hexane passed over Cr2<\/sub>O3<\/sub> supported on alumina at 873 k gives benzene.
\n\"Samacheer<\/p>\n

(ii) Toluene
\n\"Samacheer\"Samacheer<\/p>\n

\"Samacheer<\/p>\n

Question 9.
\nWhat happens when methane reacts with steam?
\nAnswer:
\nMethane reacts with steam at 1273K in the presence of Nickel and decomposes to form carbon monoxide and hydrogen gas.
\nCH4<\/sub>(g) + H2<\/sub>O(g) \"Samacheer CO(g) + 3H2<\/sub>
\nProduction of H2<\/sub> gas from methane is known as steam reforming process and it is a well-established industrial process for the production of H2<\/sub> gas from hydrocarbons.<\/p>\n

Question 10.
\nExplain the Isomerisation reaction with suitable example.
\nAnswer:
\nIsomerisation is a chemical process by which a compound is transformed into any its isomeric forms. Normal alkanes can be converted into branched alkanes in the presence of AlCl3<\/sub> and HCl at 298 k.
\n\"Samacheer
\nThis process is of great industrial importance. The quality of gasoline is improved by isomerizing its components.<\/p>\n

Question 11.
\nWhat is isomerism? Mention the types of isomerism?
\nAnswer:
\nThe phenomenon in which the same molecular formula may exhibit different structural arrangements is called isomerism.
\nThere are two types of isomerism. namely.<\/p>\n

    \n
  • Structural isomerism<\/li>\n
  • Stereoisomerism<\/li>\n<\/ul>\n

    Question 12.
    \nExplain the Geometrical isomerism of alkene with suitable example.
    \nAnswer:
    \nIt is a type of stereoisomerism and it is also called cis-trans isomerism. Such type of isomerism results due to the restricted rotation of doubly bounded carbon atoms.
    \nIf the similar groups lie on the same side, then the geometrical isomers are called Cis-isomers. When the similar groups lie on the opposite side, it is called a Trans isomer.
    \nExample:
    \nThe geometrical isomers of 2-Butene is expressed as follows
    \n\"Samacheer<\/p>\n

    \"Samacheer<\/p>\n

    Question 13.
    \nWrite the test for Alkene.
    \nAnswer:
    \nBromine in water is reddish brown colour. When small about of bromine water is added to an alkene, the solution is decolourised as it forms dibromo compound. So, this is the characteristic test for unsaturated compounds.
    \nExample:
    \n\"Samacheer<\/p>\n

    Question 14.
    \nMention uses of Alkenes.
    \nAnswer:<\/p>\n

      \n
    • Alkenes find many diverse applications in industry. They are used as starting materials in the synthesis of alcohols, plastics, liquors, detergents and fuels<\/li>\n
    • Ethene is the most important organic feed stock in the polymer industry. E.g,’ PVC, Sarans and polyethylene. These polymer are used in the manufacture of floor tiles, shoe soles, synthetic fibres,raincoats, pipes etc.<\/li>\n<\/ul>\n

      Question 15.
      \nHow is propyne prepared from propylidine chloride?
      \nAnswer:<\/p>\n

      \"Samacheer<\/p>\n

      Question 16.
      \nHow is ethyne prepared from CaC2<\/sub>?
      \nAnswer:
      \nEthyne can be manufactured in large scale
      \nby action of calcium carbide with water.
      \n\"Samacheer
      \nCalcium carbide needed for this reaction is prepared by heating quick lime and coke in an electric furance at 3273 K
      \nCaO + 3C \"Samacheer CaC2<\/sub> + CO<\/p>\n

      \"Samacheer<\/p>\n

      Question 17.
      \nWrite the reaction of propyne using Br2<\/sub>.
      \nAnswer:
      \n\"Samacheer
      \nWhen Br2<\/sub> in CCl4<\/sub> (Reddishbrown) is added to an aikyne, the colour is decolounsed. This is the test for unsaturation.<\/p>\n

      Question 18.
      \nMention the uses of alkynes.
      \nAnswer:<\/p>\n

        \n
      1. Acetylene is used in oxy acetylene torch used for welding and cutting metals.<\/li>\n
      2. It is used for manufacture of PVC, polyvinyl acetate, polyvinyl ether, orlon and neoprene rubbers.<\/li>\n<\/ol>\n

        \"Samacheer<\/p>\n

        III. Short question and answers (3 Marks):<\/span><\/p>\n

        Question 1.
        \nHow are the following conversions carried out?
        \n(i) propene \u2192 propane
        \n(ii) ethene \u2192 ethane
        \n(iii) prop – 1 – yne \u2192 propane
        \nAnswer:
        \n(i) propene \u2192 propane
        \nCH3<\/sub> – CH = CH2<\/sub> + H2<\/sub> \"Samacheer CH3<\/sub> – CH2<\/sub> – CH3<\/sub>
        \npropene\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0propane<\/p>\n

        (ii) ethene \u2192 ethane
        \nCH2<\/sub> = CH2<\/sub> + H2<\/sub> \"Samacheer CH3<\/sub> – CH3<\/sub>
        \nethene\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0ethane<\/p>\n

        (iii) prop – 1 – yne \u2192 propane
        \nCH3<\/sub> – C \u2261 CH + 2H2<\/sub> \"Samacheer CH3<\/sub> – CH2<\/sub> – CH3<\/sub>
        \nprop – 1 – yne\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 propane<\/p>\n

        Question 2.
        \nwrite the IUPAC name of the following compounds.
        \n\"Samacheer
        \nAnswer:
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 3.
        \nWrite the structural formula for the following compounds.
        \n(i) 3 – Ethyl – 4, 5 – dipropyl octane
        \n(ii) 2, 3 – Dimethyl pentane
        \n(iii) 4 – Ethyl – 2,7 – Dimethyl octane
        \nAnswer:
        \n(i) 3 – Ethyl – 4, 5 – dipropyl octane
        \n\"Samacheer<\/p>\n

        (ii) 2, 3 – Dimethyl pentane
        \n\"Samacheer<\/p>\n

        (iii) 4 – Ethyl – 2,7 – Dimethyl octane
        \n\"Samacheer<\/p>\n

        Question 4.
        \nWrite a short note on
        \n(i) Wurtz reaction
        \n(ii) Corey – House Mechanism
        \nAnswer:
        \n(i) Wurtz reaction:
        \nWhen a solution of halo alkanes in dry ether is treated with sodium metal, higher alkanes are produced. This reaction is used to prepare higher alkanes with even number of carbon atoms.
        \nExample:
        \nCH3<\/sub> – Br + 2Na + Br – CH3<\/sub> \"Samacheer CH3<\/sub> – CH3<\/sub> + NaBr
        \nmethyl bromide\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 ethane<\/p>\n

        (ii)Corey-House Mechanism:
        \nAn alkyl halide and lithium di alkyl cuprate are reacted to give higher alkane.
        \nExample:
        \nCH3<\/sub>CH2<\/sub>Br + (CH3<\/sub>)2<\/sub>LiCu \u2192 CH3<\/sub>CH2<\/sub>CH3<\/sub> + CH3<\/sub>Cu + LiBr
        \nEthyl bromide<\/p>\n

        \"Samacheer<\/p>\n

        Question 5.
        \nHow is methane prepared from Grignard reagent?
        \nAnswer:
        \nMethyl chloride reacts with magnesium in presence of dry ether gives methyl magnesium chloride. Then methyl magnesium chloride reacts with water to give methane.
        \nCH3<\/sub> – Cl + Mg \"Samacheer CH3<\/sub>MgCl
        \nchloromethane\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0methyl magnesium chloride<\/p>\n

        CH3<\/sub>MgCl + H2<\/sub>O \u2192 CH4<\/sub> + Mg(OH)Cl
        \nmethane<\/p>\n

        Question 6.
        \nWhat is meant by pyrolysis? Explain the pyrolysis reaction of Ethane and propane.
        \nAnswer:
        \nPyrolysis is defined as the thermal decomposition of organic compound into smaller fragments in the absence of air through the application of heat. ‘Pyro’ means ‘fire’ and ‘lysis’ means ‘separating’. Pyrolysis of alkanes also named as cracking.<\/p>\n

        In the absence of air, when alkane vapours are passed through red-hot metal it breaks down into simpler hydrocarbons.<\/p>\n

        1) \"Samacheer<\/p>\n

        2) 2CH3<\/sub> – CH3<\/sub> \"Samacheer\u00a0 CH2<\/sub> = CH2 <\/sub>+ 2CH4<\/sub>
        \nEthane\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0Ethylene<\/p>\n

        Question 7.
        \nMention the uses of alkanes.
        \nAnswer:
        \nThe exothermic nature of alkane combustion reaction explains the extensive use of alkanes as fuels. Methane present in natural gas is used in home heating. Mixture of propane and butane are known as LPG gas which is used for domestic cooking purpose. GASOLINE is a complex mixture of many hydrocarbons used as a fuel for internal combustion engines.<\/p>\n

        Carbon black is used in the manufacture of ink, printer ink and black pigments. It is also used s fillers.
        \n\"Samacheer<\/p>\n

        Question 8.
        \nWrite all possible structural isomers with the molecular formula C4<\/sub>H10<\/sub> and name them.
        \nAnswer:
        \n(i) CH3<\/sub> – CH = CH – CH3<\/sub> 2 – butene
        \n(ii) CH2<\/sub> = CH – CH2<\/sub> – CH3<\/sub> 1 – butene
        \n(iii) \"Samacheer 2 – mehyl – 1 – propene
        \nstructures (i) 8s (ii) are position isomers, structures (i) & (iii), (ii) 8s (iii) are chain isomers.<\/p>\n

        \"Samacheer<\/p>\n

        Question 9.
        \nHow is ethene prepared by Kolbe\u2019s electrolytic method?
        \nAnswer:
        \nWhen an aqueous solution of potassium succinate is electrolyzed between two platinum electrodes, ethene is produced at the anode.
        \n\"Samacheer<\/p>\n

        Question 10.
        \nHow are the following compounds prepared by ozonolysis method?
        \n(i) Formaldehyde
        \n(ii) Acetaldehyde
        \nAnswer:
        \n(i) Formaldehyde:
        \n\"Samacheer<\/p>\n

        (ii) Acetaldehyde:
        \n\"Samacheer<\/p>\n

        Question 11.
        \nHow ozone reacts with 2 – methyl propene?
        \nAnswer:
        \n\"Samacheer
        \nWhen 2 – methyl propene reacts with ozone to give ozonoid. Ozonide is treated with Zn\/H2<\/sub>O gives acetone.<\/p>\n

        Question 12.
        \nHow is acetylene prepared from ethylene?
        \nAnswer:
        \nThis process involves two steps:
        \n(i) Halogenation of alkenes to form vicinal dihalides
        \n(ii) Dehalogenation of vicinal dihalides to form alkynes.
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 13.
        \nHow is acetylene prepared by Kolbe\u2019s electrolytic method?
        \nAnswer:
        \nElectrolysis of sodium or potassium salt of maleic or fumaric acid yields alkynes.
        \n\"Samacheer<\/p>\n

        Question 14.
        \nWrite Ozonolysis reaction of Propyne?
        \nAnswer:
        \n\"Samacheer<\/p>\n

        Question 15.
        \nHow is BHC prepared? Give its uses.
        \nAnswer:
        \nChlorination of Benzene:
        \nBenzene reacts with three molecules of Cl2<\/sub> in the presence of sun light or UV light to yield Benzene Hexa Chloride (BHC) C6<\/sub>H6<\/sub>Cl6<\/sub>. This is known as gammaxane or Lindane which is a powerful insecticide.
        \n\"Samacheer<\/p>\n

        Question 16.
        \nHow propane is prepared form 1, 2 – dichloro propane?
        \nAnswer:
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 17.
        \nExplain the polymerization reaction of alkenes.
        \nAnswer:
        \nA polymer is a large molecule formed by the combination of larger number of small molecules. The process is known as polymensation. Alkenes undergo polymerisation at high temperature and pressure, in the presence of a catalyst.
        \nExample:
        \nred hot
        \n\"Samacheer<\/p>\n

        Question 18.
        \nWrite a note on acidic nature of Alkynes.
        \nAnswer:
        \nAn alkyne shows acidic nature only if it contains terminal hydrogen. This can be explained by considering sp hybrid orbitals of carbon atom in alkynes. The percentage of S-character of sp hybrid orbital (50%) is more than sp2<\/sup> hybrid orbital of alkene (33%) and sp3<\/sup> hybrid orbital of alkane (25%). Because of this, Carbon becomes more electronegative facilitating donation of H+ ions to bases. So hydrogen attached to triply bonded carbon atoms is acidic but not the others.
        \n\"Samacheer<\/p>\n

        Question 19.
        \nWrite a short note on
        \n(i) Wurtz – Fittig reactions
        \n(ii) Friedel Craft\u2019s reaction
        \nAnswer:
        \n(i) Wurtz – Fittig reactions:
        \nWhen a solution of bromo benzene and iodo methane in dry ether is treated with metallic sodium, toluene is formed.
        \n\"Samacheer<\/p>\n

        (ii) Friedel Craft\u2019s reaction:
        \nWhen benzene is treated with methyl chloride in the presence of anhydrous aluminium chloride, toluene is formed.
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        IV. Long Question and answers (5 Marks):<\/span><\/p>\n

        Question 1.
        \nHow to draw structural formula for given IUPAC name with suitable example.
        \nAnswer:
        \nAfter you learn the rules for naming alkanes, it is relatively easy to reverse the procedure and translate the name of an alkane into a structural formula. The example below show how this is done.
        \nLet us draw the structural formula for
        \n3 – ethyl – 2, 3 – dimethyl pentane
        \nStep 1:
        \nThe parent hydrocarbon is pentane. Draw the chain of five carbon atoms and number it. .
        \n\"Samacheer<\/p>\n

        Step 2:
        \nComplete the carbon skeleton by attaching the alkyl group as they are specified in the name. An ethyl group is attached to carbon 3 and two methyl groups are attached to carbon 2 and 3.
        \n\"Samacheer<\/p>\n

        Step 3:
        \nAdd hydrogen atoms to the carbon skeleton so that each carbon atoms has four bonds.
        \n\"Samacheer<\/p>\n

        Question 2.
        \nExplain the conformations of ethane.
        \nAnswer:
        \nThe two tetrahedral methyl groups can rotate about the carbon – carbon bond axis yielding several arrangements called conformers. The extreme conformations are staggered and eclipsed conformation. There can be number of other arrangements between staggered and eclipsed forms and their arrangements are known as skew forms.
        \nEclipsed conformation:
        \n\"Samacheer<\/p>\n

        In this conformation, the hydrogen\u2019s of one carbon are directly behind those of the other. The repulsion between the atoms is maximum and it is the least stable conformer.<\/p>\n

        Staggered conformation:
        \n\"Samacheer<\/p>\n

        In this conformation, the hydrogen\u2019s of both the carbon atoms are far apart from each other. The repulsion between the atoms is minimum and it is the most stable conformation.<\/p>\n

        Skew conformation:<\/p>\n

        The infinite numbers of possible intermediate conformations between the two extreme conformations are referred as skew conformations. The stabilities of various conformations of ethane are:
        \nStaggered > Skew > Eclipsed
        \nThe potential energy difference between the staggered and eclipsed conformation of ethane is around 12.5 kJmol-1<\/sup>. The various conformations can be represented by new man projection formula.
        \n\"Samacheer<\/p>\n

        Eclipsed Skew Staggered newmann projection formula for Ethane.<\/p>\n

        \"Samacheer<\/p>\n

        Question 3.
        \nExplain the steps involved in the mechanism of halogenations of alkane.
        \nHalogenation:
        \nA Halogenation reaction is the chemical reaction between an alkane and halogen in which one or more hydrogen atoms are substituted by the halogens.<\/p>\n

        Chlorination and Bromination are two widely used halogenation reactions. Fluorination is too quick and iodination too slow. Methane reacts with chlorine in the presence of light or when heated as follows.
        \n\"Samacheer<\/p>\n

        Mechanism:
        \nThe reaction proceeds through the free radical chain mechanism. This mechanism is characterized by three steps initiation, propagation and termination.<\/p>\n

        (i) Chain Initiation:
        \nThe chain is initiated by UV light leading to homolytic fission of chlorine molecules into free radicals (chlorine atoms).
        \n\"Samacheer<\/p>\n

        Here we choose Cl – Cl bond for fission because C – C & C – H bonds are stronger than Cl – Cl.<\/p>\n

        ii) Propagation:
        \nIt proceeds as follows
        \na) Chlorine free radial attacks the methane molecule and breaks the C – H bond resulting in the generation of methyl free radical
        \n\"Samacheer<\/p>\n

        b) The methyl free radical thus obtained attacks the second molecule of chlorine to give chloromethane (CH3<\/sub>Cl) and a chlorine free radical as follows.
        \n\"Samacheer<\/p>\n

        c) This chlorine free radical then cycles back to step a) and both step a) and b) are repeated many times and thus chain of reaction is set up.<\/p>\n

        iii) Chain termination:
        \nAfter sometimes, the reactions stops due to consumption of reactant and the chain is terminated by the combination of free radicals.
        \n\"Samacheer<\/p>\n

        Question 4.
        \nWrite the IUPAC name of the following compounds.
        \n1) CH3<\/sub> – CH = CH2<\/sub>
        \n2) CH3<\/sub> – CH = CH – CH3<\/sub>
        \n3) \"Samacheer
        \n4) \"Samacheer
        \nAnswer:
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 5.
        \nWrite the IUPAC name of the following compounds.
        \n\"Samacheer
        \nAnswer:
        \n1) \"Samacheer<\/p>\n

        2) \"Samacheer<\/p>\n

        3) \"Samacheer<\/p>\n

        4) \"Samacheer<\/p>\n

        Question 6.
        \nDraw the structures for the following alkenes.
        \n(i) 6 – Bromo – 2, 3 – dimethyl – 2 – hexene
        \n(ii) 5 – Bromo – 4 – chloro – 1 -heptene
        \n(iii) 2, 5 – dimethyl – 4 – octene
        \n(iv) 4 – Methyl – 2 – pentene
        \nAnswer:
        \n(i) 6- Bromo – 2, 3-dimethyl – 2 -hexene
        \n\"Samacheer<\/p>\n

        (ii) 5 – Bromo – 4 – chloro – 1 -heptene
        \n\"Samacheer<\/p>\n

        (iii) 2, 5 – dimethyl – 4 – octene
        \n\"Samacheer<\/p>\n

        (iv) 4 – Methyl – 2 – pentene
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 7.
        \nDraw the structure and write down the IUPAC name for the isomerism exhibited by the molecular formulae:
        \n(i) C5<\/sub>H12<\/sub> – Pentene (3 isomers)
        \n(ii) C6<\/sub>H14<\/sub> – Hexene (5 isomers)
        \n(iii) C5<\/sub>H12<\/sub> – Pentene (3 isomers)
        \nAnswer:
        \n(i) C5<\/sub>H12<\/sub> – Pentene
        \na) CH3<\/sub> – CH2<\/sub> – CH2<\/sub> – CH = CH2<\/sub>
        \n1 – Pentene<\/p>\n

        b) \"Samacheer
        \n2 – methyl – 2 – butene<\/p>\n

        c) CH3<\/sub>CH = CH – CH2<\/sub>CH3<\/sub>
        \n2 – pentene<\/p>\n

        (ii) C6<\/sub>H14<\/sub> – Hexene
        \na) CH3<\/sub> – CH2<\/sub> – CH2<\/sub> – CH2<\/sub> – CH = CH2<\/sub>
        \n1 – hexane<\/p>\n

        b) CH3<\/sub> – CH2<\/sub> – CH2<\/sub> – CH = CH – CH3<\/sub>
        \n2 – hexane<\/p>\n

        c) CH3<\/sub> – CH2<\/sub> – CH = CH – CH3<\/sub> – CH2<\/sub>
        \n3 – hexane<\/p>\n

        d) \"Samacheer<\/p>\n

        e) \"Samacheer<\/p>\n

        Question 8.
        \nHow are the following conversions carried out?
        \n(i) ethanol \u2192 ethene
        \n(ii) 2- butyne cis \u2192 2 – butene and trans – 2 – butane
        \n(iii) 1 – bromopropane \u2192 prop – 1 – ene
        \n(iv) 1 – 2 – dibromoethane – ethene
        \nAnswer:
        \n1) ethanol \u2192 ethene
        \nC2<\/sub>H5<\/sub>OH \"Samacheer H2<\/sub>C = H2<\/sub>C
        \nethanol ethane<\/p>\n

        (ii) 2 – butyne \u2192 cis – 2 – butene
        \nH3<\/sub>C – C \u2261 C – CH3<\/sub> + H2<\/sub> \"Samacheer<\/p>\n

        2 – butane \u2192 trans – 2 – butane
        \n\"Samacheer<\/p>\n

        (iii) 1 – bromopropane \u2192 prop – 1 – ene
        \nH3<\/sub>C – CH2<\/sub> – CH2<\/sub> – Br \"Samacheer H3<\/sub>C – CH = CH2<\/sub> + KBr + H2<\/sub>O
        \n1 – bromopropane \u2192 prop – 1 – ene<\/p>\n

        (iv) 1 – 2 – dibromoethane – ethene
        \n\"Samacheer
        \n1 – 2 – dibromoethane – ethene<\/p>\n

        \"Samacheer<\/p>\n

        Question 9.
        \nWrite the mechanism involved in the addition of HBr to alkene in the presence of organic peroxide.
        \nAnswer:
        \nAnti-Markovnikoff\u2019s Rule (Or) Peroxide Effect (Or) KharaschAddition:
        \nThe addition of HBr to an alkene in the presence of organic peroxide takes place in the direction opposite to that predicted by Markovnikoff\u2019s rule.
        \nCH3<\/sub> – CH = CH2<\/sub> + HBr \"Samacheer CH3<\/sub> – CH2<\/sub> – CH3<\/sub> – CH2<\/sub> – CH2<\/sub> – Br
        \nprop – 1 – ene\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 1 – bromopropane<\/p>\n

        Mechanism:
        \nThe reaction proceeds via free radical mechanism.<\/p>\n

        Step 1:
        \nThe week O – O single bond linkages of peroxides undergoes homolytic cleavage to generate free radical.
        \n\"Samacheer<\/p>\n

        Step 2:
        \nThe radicals abstract H from HBr thus generating bromine radical.
        \n\"Samacheer<\/p>\n

        Step 3:
        \nThe Bromine radical adds to the double bond in the way to form more stable alkyl free radical.
        \n\"Samacheer<\/p>\n

        Step 4:
        \nAddition of HBr to secondary free radical
        \n\"Samacheer<\/p>\n

        Step 5:
        \nAddition of HBr to primary free radical
        \n\"Samacheer<\/p>\n

        Question 10.
        \nHow are the following conversions carried out?
        \nAnswer:
        \n(i) Propene \u2192 2 – Propanol
        \n(ii) ethene \u2192 ethylene glycol
        \n(iii) 2 – butene \u2192 Acetic acid
        \n(iv) 2 – methyl – 1 – propene \u2192 Acetone
        \nAnswer:
        \n(i) Propene \u2192 2 – Propanol
        \n\"Samacheer<\/p>\n

        (ii) ethene \u2192 ethylene glycol
        \n\"Samacheer<\/p>\n

        (iii) 2 – butene \u2192 Acetic acid
        \n\"Samacheer<\/p>\n

        (iv) 2 – methyl – 1 – propene \u2192 Acetone
        \n\"Samacheer \"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 11.
        \nAn organic compound (A) C2<\/sub>H4<\/sub> decolourises bromine water. (A) on reaction with chlorine gives (B) A reacts with HBr to give (C). Identity (A), (B), (C). Explain th. reactions.
        \nAnswer:
        \n\"Samacheer
        \nResult:
        \n(A) – ethylene
        \n(B) – 1, 2 – dichloroethane
        \n(C) – ethyl bromide<\/p>\n

        Question 12.
        \nHow are the following conversions carried out?
        \n(i) 2 – butyne \u2192 2, 2 – dichlorobutane
        \n(ii) 1 – butyne \u2192 2, 2 – dibromobutane
        \n(iii) ethyne \u2192 acetaldehyde
        \n(iv) Propyne \u2192 propan – 2 – one
        \nAnswer:
        \n(i) 2 – butyne \u2192 2, 2 – dichlorobutane
        \n\"Samacheer<\/p>\n

        (ii) 1 – butyne \u2192 2, 2 – dibromobutane
        \n\"Samacheer<\/p>\n

        (iii) ethyne \u2192 acetaldehyde
        \n\"Samacheer<\/p>\n

        (iv) Propyne \u2192 propan – 2 – one
        \n\"Samacheer<\/p>\n

        Question 13.
        \nHow are the following compounds prepared from ethyne?
        \n(i) Formic acid
        \n(ii) Vinyl ethylene
        \n(iii) Benzene
        \nAnswer:
        \n(i) Formic acid
        \n\"Samacheer<\/p>\n

        (ii) Vinyl ethylene
        \n2CH \u2261 CH \"Samacheer CH2<\/sub> = CH – C \u2261 CH (Vinyl ethylene)<\/p>\n

        (iii) Benzene
        \n\"Samacheer<\/p>\n

        Question 14.
        \nExplain the Huckel\u2019s rule of Aromaticity.
        \nAnswer:
        \nHuckel proposed that aromaticity is a function of electronic structure. A compound may be aromatic, if it obeys the following rules (Huckel\u2019s rule)
        \ni) The molecule must be co-planar
        \nii) Complete delocalization of n electron in the ring
        \niii) Presence of (4n+2) n electrons in the ring where n is an integer (n = 0,1,2….)
        \nThis is known as Huckle\u2019s rule.
        \nSome of the examples which obey Huckel rule.<\/p>\n

        1. The benzene ring is planar with delocalized \u03c0 electrons (6)
        \nIt obeys Huckel\u2019s rule because 4n + 2 = (4 \u00d7 1) + 2 = 6\u03c0 electrons.
        \nHence, it is an aromatic compound
        \n\"Samacheer<\/p>\n

        2. It has planar ring structure with delocalized \u03c0 electrons (10).
        \nApplying Huckle\u2019s rule (4 \u00d7 2) + 2 = 10\u03c0 electrons.
        \nHence it is an aromatic compound
        \n\"Samacheer
        \nNaphthalene<\/p>\n

        3. It has a planar ring structure with delocalized \u03c0 electrons(14).
        \nApplying Huckle\u2019s rule (4 \u00d7 3) + 2 = 14\u03c0 electrons.
        \n\"Samacheer<\/p>\n

        4. It has planar ring structure but the \u03c0 electrons are not delocalized.
        \nApplying Huckle\u2019s rule (4 \u00d7 1) + 2 = 6\u03c0 electrons.
        \nBut it has only 4electrons. So it is not an aromatic compound
        \n\"Samacheer<\/p>\n

        5. It has a tub shaped ring structure. It does not obey Huckel\u2019s rule.
        \nApplying Huckle\u2019s rule 4n + 2 = 8\u03c0 electrons if n = 2
        \nSo it is not an aromatic compound.
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 15.
        \nExplain the Kekule\u2019s structure of benzene.
        \nAnswer:
        \nIn 1865, August Kekule suggested that benzene consists of a cyclic planar structure of six carbon with alternate single and double bonds.
        \nThere were two objections:
        \n(i) Benzene forms only one orthodisubstituted products whereas the Kekule\u2019s structure predicts two o-di substituted products as shown below.
        \n\"Samacheer
        \nPresence of double bond between the substituents<\/p>\n

        \"Samacheer
        \nPresence of single bond between the substituents<\/p>\n

        (ii) Kekule\u2019s structure failed to explain why benzene with three double bonds did not give addition reactions like other alkenes.To overcome this objection, Kekule suggested that benzene was mixture of two forms (1 and 2) in rapid equilibrium.
        \n\"Samacheer<\/p>\n

        Question 16.
        \nExplain the resonance in benzene.
        \nAnswer:
        \nThe phenomenon in which two or more structures can be written for a substance which has identical portions of atoms in called resonance. The actual structure of the molecule is said to be resonance hybrid of various possible alter nature structures. In benzene, Kekule\u2019s structures I & II represented the resonance structure, and structure III is the resonance hybrid of structure I & II.
        \n\"Samacheer<\/p>\n

        The structures 1 and 2 exist only in theory. The actual structure of benzene is the hybrid of two hypothetical resonance structures.<\/p>\n

        \"Samacheer<\/p>\n

        Question 17.
        \nWrite the industrial preparation of benzene from coal tar.
        \nAnswer:
        \nCoal tar is a viscous liquid obtained by the pyrolysis of coal. During fractional distillation, coal tar is heated and distills away its volatile compounds namely benzene, toluene, xylene in the temperature range of 350 to 443 K. These vapours are collected at the upper part of the fractionating column
        \n\"Samacheer<\/p>\n

        Question 18.
        \nHow is benzene prepared from
        \n(i) Acetylene
        \n(ii) Decarboxylation
        \n(iii) Phenol
        \nAnswer:
        \n(i) From acetylene
        \nAcetylene on passing through a red -hot tube trimerises to give benzene. We havealready studied this concept in polymerization of alkynes.
        \n\"Samacheer<\/p>\n

        (ii) Decarboxylation of aromatic acid.
        \nWhen sodium benzonate is heated with sodalime, benzene vapours distil over.
        \nC6<\/sub>H5<\/sub>COONa + NaOH \"Samacheer C6<\/sub>H6<\/sub> + Na2<\/sub>CO3<\/sub><\/p>\n

        (iii) Preparation of benzene from Phenol
        \nWhen phenol vapours are passed over zinc dust, then it is reduced to benzene.
        \nC6<\/sub>H6<\/sub>OH + Zn \"Samacheer\u00a0C6<\/sub>H6<\/sub> + ZnO<\/p>\n

        Question 19.
        \nExplain Electrophilic substitution reaction of benzene.
        \nAnswer:
        \n(i) nitration:
        \nWhen benzene is heated at 330K with a nitrating mixture (Con. HNO3<\/sub> + Con. H2<\/sub>SO4<\/sub>), nitro benzene is formed by replacing of hydrogen atom by nitronium ion NO2<\/sub>+<\/sup> (electrophile).
        \n\"Samacheer
        \nConcentrated H2<\/sub>SO4<\/sub> is added to produce nitronium ion NO2<\/sub>+<\/sup>.<\/p>\n

        (ii) Halogenation:
        \nBenzene reacts with halogens (X2<\/sub> = Cl2<\/sub>, Br2<\/sub>,) in the presence of Lewis acid such as FeCl3<\/sub>, FeBr3<\/sub> orAlCl3<\/sub> and give corresponding halo benzene.
        \n\"Samacheer<\/p>\n

        (iii) Sulphonation:
        \nBenzene reacts with fuming sulphuric acid (Con. H2<\/sub>SO4<\/sub> + SO3<\/sub>) and gives benzene sulphonic acid. The electrophile SO3<\/sub>\u00a0is a molecule.
        \n\"Samacheer<\/p>\n

        (iv) Friedel craft\u2019s alkylation: (methylation)
        \nWhen benzene is treated with a alkyl halide in the presence of only AlCl3<\/sub>, alkyl benzene is formed.
        \n\"Samacheer<\/p>\n

        (v) Friedel craft\u2019s acylatlon: (Acetylation)
        \nWhen benzene is treated with acetyichioride in the presence of AlCl3<\/sub>, acyl benzene is formed.
        \n\"Samacheer<\/p>\n

        \"Samacheer<\/p>\n

        Question 20.
        \nHow is benzene converted into
        \na) Cyclo hezane
        \nb) maleic anhydride
        \nc) 1, 4 cyclo hexadiene
        \nAnswer:
        \na) Cyclo hexane:
        \nBenzene reacts with hydrogen in the presence of Platinum or Palladium to yield Cyclohexane. This is known as hydrogenation.
        \n\"Samacheer<\/p>\n

        b) maleic anhydride:
        \nAlthough benzene is very stable to strong oxidizing agents, it quickly undergoes vapour phase oxidation by passing its vapour mixed with oxygen over V2<\/sub>O5<\/sub> at 773k. The ring breaks to give maleic anhydride.
        \n\"Samacheer<\/p>\n

        c) 1, 4 cyclo hexadiene:
        \nBenzene can be reduced to non- conjugated dienes 1, 4 – cyclohexadiene by treatment with Na or Li in a mixture of liquid ammonia and alcohol. It is the convenient method to prepare cyclicdienes.
        \n\"Samacheer<\/p>\n","protected":false},"excerpt":{"rendered":"

        Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide Pdf Chapter 13 Hydrocarbons Text Book Back Questions and Answers, Notes. Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 13 Hydrocarbons 11th Chemistry Guide Hydrocarbons Text Book Back Questions and Answers Textbook Evaluation: I. Choose the best answer: Question 1. The correct statement regarding the comparison …<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[6],"tags":[],"class_list":["post-36987","post","type-post","status-publish","format-standard","hentry","category-class-11"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/36987"}],"collection":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/comments?post=36987"}],"version-history":[{"count":1,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/36987\/revisions"}],"predecessor-version":[{"id":41747,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/36987\/revisions\/41747"}],"wp:attachment":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/media?parent=36987"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/categories?post=36987"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/tags?post=36987"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}