Tamilnadu State Board New Syllabus Samacheer Kalvi 8th Social Science Guide Pdf Geography Chapter 5 v Text Book Back Questions and Answers, Important Questions, Notes.

Tamilnadu Samacheer Kalvi 8th Social Science Solutions Geography Chapter 5 Hazards

Samacheer Kalvi 8th Social Science Hazards Text Book Back Questions and Answers

I. Choose the correct answer.
1. ………………. percentage of nitrogen is present in the air.
a) 78.09%
b) 74.08%
c) 80.07%
d) 76.63%
Answer:
a) 78.09%

2. Tsunami in the Indian Ocean took place in the year ………………. .
a) 1990
b) 2004
c) 2005
d) 2008
Answer:
b) 2004

3. The word tsunami is derived from ………………. language.
a) Hindi
b) French
c) Japanese
d) German
Answer:
c) Japanese

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

4. The example of surface water is
a) Artesian well
b) Groundwater
c) Subsurface water
d) Lake
Answer:
d) Lake

5. Event that occurs due to the failure of monsoons.
a) Condensation
b) Drought
c) Evaporation
d) Precipitation
Answer:
b) Drought

II. Fill in the blanks.

1. Hazards may lead to …………….
Answer:
affect the community most severely

2. Landslide is an example of …………… hazard.
Answer:
geologic

3. On the basis of origin, the hazard can be grouped into …………… categories.
Answer:
8 (or) eight

4. Terrorism is an example of …………… hazard.
Answer:
human-induced

5. Oxides of nitrogen are …………… pollutants which affect human beings.
Answer:
primary

6. Chernobyl nuclear accident took place in
Answer:
26th April 1986

III. Match the following.

List I List II
1. Primary pollutant a. Terrorism
2. Hazardous waste b. Tsunami
3. Earthquake c. Outdated drugs
4. Meteorological drought d. Oxides of sulphur
5. Human induced hazard e. Reduction in rainfall

Answer:

List I List II
1. Primary pollutant d. Oxides of sulphur
2. Hazardous waste c. Outdated drugs
3. Earthquake b. Tsunami
4. Meteorological drought e. Reduction in rainfall
5. Human induced hazard a. Terrorism

IV. Answer in brief.
1. Define ‘hazard’?
Answer:
‘Hazards are defined as a thing, person, event or factor that poses a threat to people, structures or economic assets and which may cause a disaster.’

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

2. What are the major types of hazards?
Answer:

  • Natural hazards
  • Human-made hazards
  • Socio-natural hazards

3. Write a brief note on hazardous wastes.
Answer:
The wastes that may or tend to cause adverse health effects on the ecosystem and human beings are called hazardous wastes.

4. List out the major flood-prone areas of our country.
Answer:
Punjab, West Bengal, Odisha are the region which is also prone to flood often.

5. Mention the types of drought.
Answer:
Drought could be classified into three types. They are:

  1. Meteorological drought
  2. Hydrological drought
  3. Agricultural drought

6. Why should not we construct houses in foothill areas?
Answer:
Because of the presence of steep slopes and heavy rainfall we should not construct houses at the foothills areas.

V. Distinguish the following.
1. Hazards and disasters.

Hazards Disasters
Hazards occur frequently and threaten people. It is a hazardous event that occurs over a limited time span.
Ex: Natural hazards, Earthquake. Ex: Flood

2. Natural hazards and human-made hazards.

Natural hazard Human-made hazard
Man has no role to play in such hazards. These are caused by the undesirable activities of humans.
Ex: Flood, drought, etc. Ex: Pollution of air and water

3. Flood and drought.

Flood Drought
It occurs through heavy rainfall. It occurs through no rainfall.
It is often held in the coastal Andhra Pradesh & Odisha. The dry region has seen in the leeward side of Western ghats.

4. Earthquake and tsunami.

Earthquake Tsunami
The violent tremor of the earth’s crust is called an Earthquake. Tsunami refers to huge ocean waves caused by landslides.
The study of earthquakes is called Seismograph. The study of the Tsunami is called Oceanography.

VI. Answer in a paragraph.
1. Write an essay on air pollution.
Answer:
Pollution of Air:

  1. Air is a mixture of several gases.
  2. The main gases are nitrogen (78.09%) for forming products such as fertilizers for plants and for making the air inert, oxygen (20.95%) for breathing and carbon dioxide (0.03%) for photosynthesis.
  3. Some other gases like argon, neon, helium, krypton, hydrogen, zenon and methane are also present.
  4. Air pollution is the contamination of indoor or outdoor air by a range of gases. Air pollution can be categorized into primary and secondary pollutants.
  5. A primary pollutant is an air pollutant emitted directly from a source.
  6. A secondary pollutant is not directly emitted.
  7. Primary pollutants are as follows:
    • Oxides of Sulphur
    • Oxides of Nitrogen
    • Oxides of Carbon
    • Particulate Matter and
    • Other primary pollutants
  8. Secondary pollutants are as follows:
    • Ground Level Ozone
    • Smog

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

2. Define earthquake and list out its effects.
Answer:
Earthquakes:

  • Earthquake is a violent tremor in the earth’s crust, sending out a series of shock waves in all directions from its place of origin.
  • Earthquake-prone regions of the country have been identified on the basis of scientific inputs relating to seismicity, earthquakes that occurred in the past, and the tectonic setup of the region.
  • Based on these inputs, the Bureau of Indian Standards has grouped the country into four seismic zones: Zone II, Zone III, Zone IV, and Zone V (No area of India is classified as Zone I).
    Seismic Zones Level of Risk
    Zone V Very High
    Zone IV High
    Zone III Moderate
    Zone II Low

3. Give a detailed explanation of the causes of landslides.
Answer:

1. Landslide is a rapid downward movement of rock, soil, and vegetation down the slope under the influence of gravity.

2. The causes of landslides are wide-ranging, They have two aspects in common.

3. Force of gravity and

4. Failure of Soil

5. Landslides are considered of two types. They are:

  • Naturally occurring disaster.
  • Human-induced changes in the environment.

6. Natural causes of landslides are:

  • Climatic changes
  • Seismic activities
  • Weathering
  • Soil erosion
  • Forest fires
  • Gravity and
  • Volcanic eruption

7. Human causes of landslides include deforestation mining, construction of roads, and railways over the mountain.

4. Elaborately discuss the effects of water pollution.
Answer:

  • It may cause a harmful effect on any living thing that drinks or uses or lives in it.
  • It may be defined as alternation in the physical, chemical, and biological characteristics of water, which may cause harmful effects in human and aquatic life.

The major causes of water pollution in India are:

  • Urbanisation
  • Industrial effluents
  • Sewages etc.
  • Agricultural runoff and improper agricultural practices
  • Seawater intrusion
  • Solid wastes

Samacheer Kalvi 8th Social Science Hazards Additional Important Questions and Answers

I. Choose the correct answer.
1. The content of Oxygen in the air is …………….
a) 20.95%
b) 21.95%
c) 22.95%
d) 23.95%
Answer:
a) 20.95%

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

2. The word ‘hazard’ Originated from the ……………. language.
a) French
b) Telugu
c) Malayalam
d) Kannada
Answer:
a) French

3. National Institute of Disaster Management located in ……………..
a) Britain
b) New Delhi
c) France
d) Japan
Answer:
b) New Delhi

4. In Tamil Nadu ……………. coastal districts are frequently affected by Storm Surges.
a) 13
b) 14
c) 15
d) 16
Answer:
a) 13

5. The areas that receive an annual rainfall of less than ……………. are the drought zone regions of India.
a) 60 cm
b) 50 cm
c) 40 cm
d) 45 cm
Answer:
a) 60 cm

6. The meaning of Tsunami is ……………..
a) Wave
b) Harbour wave
c) Storm
d) Storm wave
Answer:
b) Harbour wave

7. In ……………. the Ukraine part of Exclusion Zone was declared as a radiogical and environmental biosphere.
a) 2013
b) 2014
c) 2015
d)2016
Answer:
d) 2016

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

8. In India about ……………. of the land mass is prone to landslide hazard.
a) 15%
b) 18%
c) 19%
d) 20%
Answer:
a) 15%

9. In Trophical Cyclones the wind Speed may reach upto ……………. per hour.
a) 200 km
b) 100 km
c) 300 km
d) 400 km
Answer:
a) 200 km

10. High-Pressure Zone is mentioned in the Geographical map as ……………. letter.
a) L
b) P
c) H
d) S
Answer:
c) H

II. Fill in the blanks.
1. The meaning of hazard is ………………..
Answer:
a game of dice

2. ………………. may be worsened by the destruction of mangroves.
Answer:
Storm Surge hazard

3. ………………. is a violent tremor in the earth’s crust.
Answer:
Earthquake

4. ………………. is a strong wind circulating around a low-pressure area in the atmosphere.
Answer:
Cyclonic Storm

5. During Cyclonic the wind speed may reach upto …………. km and rainfall may record up to …………… cm.
Answer:
200, 50

6. A sudden rise of sea water due to trophical cyclone is called ………………..
Answer:
Storm Surge

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

7. ………………. and ………………. are the major causes of landslides.
Answer:
Steep slope, heavy rainfall

8. In Tamil Nadu ………………. and ………………. are frequently affected by landslides.
Answer:
Kodaikanal, Ooty

9. The gas used for Photosynthesis is ………………..
Answer:
Carbon dioxide

10. A ………………. pollutant is an air pollutant emitted directly from a Source.
Answer:
Primary

11. ………………. may be defined by alteration is the physical, chemical, and biological characteristics of water.
Answer:
Water Pollution

12. In India ………………. is perhaps the most critical components in Managing Disasters.
Answer:
prevention

13. Example for Biological hazard is ………………..
Answer:
Chicken Box

14. ………………., ………………. are Human-made hazards.
Answer:
Explosions, hazardous waste

15. Primary Pollutant example ………………..
Answer:
oxides of Sulphur

III. Match the following.

1. Geological hazard a) Floods, Coastal erosion
2. Hydrologic hazard b) Eruptions and Lava flows
3. Volcanic hazard c) Chickenpox, Smallpox
4. Environmental hazard d) Earthquakes, Tsunami
5. Biological hazard e) Soil, air

Answer:

1. Geological hazard d) Earthquakes, Tsunami
2. Hydrologic hazard a) Floods, Coastal erosion
3. Volcanic hazard b) Eruptions and Lava flows
4. Environmental hazard e) Soil, air
5. Biological hazard c) Chickenpox, Smallpox

IV. State whether the following statements are true or false.
1. Tsunami means Stormy Surge.
Answer:
False

2. A Secondary Pollutant is not directly emitted.
Answer:
True

V. Assertion and Reasons.
1. Assertion: Landslides are generally Sudden and infrequent.
Reason: The presence of Sleep Slope and heavy rainfall are the major causes of landslides.
a) A is correct but R is incorrect
b) Both A and R are incorrect
c) A is incorrect and R is correct
d) Both A and R are correct
Answer:
d) Both A and R are correct

VI. Answer in brief.
1. Define Catastrophe.
Answer:
A catastrophe is a massive disaster that requires a significant expenditure of money and a long time for recovery.

2. What are the major causes of floods?
Answer:
The major causes of floods are:
Meteorological factors

  • Heavy rainfall
  • Tropical cyclones
  • Cloudburst Physical factors
  • Large catchment area
  • Inadequate drainage arrangement

Human factors

  • Deforestation
  • Siltation
  • Faulty agricultural practices
  • Faulty irrigation practices
  • Collapse of dams
  • Accelerated urbanisation.

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

3. Write short notes on Indian Ocean Tsunami?
Answer:

  • On December 26, 2004, at 7:59 a.m. local time, an undersea earthquake with a magnitude of 9.1 struck off the coast of the Indonesian island of Sumatra.
  • The tsunami killed at least 2,25,000 people across a dozen countries, with Indonesia, Sri Lanka, India, Thailand, Somalia and Maldives, sustaining massive damage.

4. Explain Prevention Measures.
Answer:
Prevention is defined as the activities taken to prevent a natural calamity or potential hazard from having harmful effects on either people or economic assets.

VII. Distinguish the following.
1. Geologic hazard and Environmental hazard.

Geologic hazard Environmental hazard
Earthquakes, Tsunami, Landslide and Land subsidence. Pollution of soil/ air/water, Desertification, Global warming and Deforestation.

VIII. Answer in a paragraph.
1. Explain about Socio – natural hazards.
Answer:
Socio-natural hazards:
These are caused by the combined effect of natural forces and misdeeds of human. Some of the examples are:

  • The frequency and intensity of floods and droughts may increase due to indiscriminate felling of trees, particularly in the catchment areas of the rivers.
  • Landslides are caused by natural forces and their frequency, and impact may be aggravated as a result of construction of roads, houses etc., in mountainous areas, excavating tunnels and by mining and quarrying.
  • Storm surge hazards may be worsened by the destruction of mangroves.
  • Smog is a serious problem in most big urban areas. The emissions from vehicles and industries, combustion of wood and coal together combined with fog leads to smog.

2. Explain the Hazards based on their origin.
Answer:
Hazards can be grouped into eight categories
1. Atmospheric hazard:
Tropical storms, Thunderstorms, Lightning, Tornadoes, Avalanches, Heat waves, Fog and Forest fire.

2. Geologic/Seismic hazard:
Earthquakes, Tsunami, Landslide and Land subsidence.

3. Hydrologic hazard:
Floods, Droughts, Coastal erosion and Storm surges.

4. Volcanic hazard:
Eruptions and Lava flows.

Samacheer Kalvi 9th Social Science Guide Geography Chapter 7 Mapping Skills

5. Environmental hazard:
Pollution of soil/ air/water, Desertification, Global warming and Deforestation.

6. Biological hazard:
Chickenpox, Smallpox, AIDS [HIV] and Killer bees.

7. Technological hazard:
Hazardous material incidents, Fires, Infrastructure failures [Bridges, Tunnels, Dams, Nuclear and Radiological accidents].

8. Human-induced hazard:
Terrorism, Bomb blast, War, Transportation accidents and Civil disorder.

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