Samacheer Class 8 Social Science - v

a) 78.09%
2. Tsunami in the Indian Ocean took place in the year ………………. .
a) 1990
b) 2004
c) 2005
d) 2008
b) 2004
3. The word tsunami is derived from ………………. language.
a) Hindi
b) French
c) Japanese
d) German
c) Japanese4. The example of surface water is
a) Artesian well
b) Groundwater
c) Subsurface water
d) Lake
d) Lake
5. Event that occurs due to the failure of monsoons.
a) Condensation
b) Drought
c) Evaporation
d) Precipitation
b) Drought

a) 20.95%2. The word ‘hazard’ Originated from the ……………. language.
a) French
b) Telugu
c) Malayalam
d) Kannada
a) French
3. National Institute of Disaster Management located in ……………..
a) Britain
b) New Delhi
c) France
d) Japan
b) New Delhi
4. In Tamil Nadu ……………. coastal districts are frequently affected by Storm Surges.
a) 13
b) 14
c) 15
d) 16
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
a) 60 cm
6. The meaning of Tsunami is ……………..
a) Wave
b) Harbour wave
c) Storm
d) Storm wave
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
d) 20168. In India about ……………. of the land mass is prone to landslide hazard.
a) 15%
b) 18%
c) 19%
d) 20%
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
a) 200 km
10. High-Pressure Zone is mentioned in the Geographical map as ……………. letter.
a) L
b) P
c) H
d) S
c) H

affect the community most severely
2. Landslide is an example of …………… hazard.
geologic
3. On the basis of origin, the hazard can be grouped into …………… categories.
8 (or) eight
4. Terrorism is an example of …………… hazard.
human-induced
5. Oxides of nitrogen are …………… pollutants which affect human beings.
primary
6. Chernobyl nuclear accident took place in
26th April 1986

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c. Outdated drugs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

‘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.’2. What are the major types of hazards?
Natural hazards
Human-made hazards
Socio-natural hazards
3. Write a brief note on hazardous wastes.
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.
Punjab, West Bengal, Odisha are the region which is also prone to flood often.
5. Mention the types of drought.
Drought could be classified into three types. They are:
Meteorological drought
Hydrological drought
Agricultural drought
6. Why should not we construct houses in foothill areas?
Because of the presence of steep slopes and heavy rainfall we should not construct houses at the foothills areas.

Pollution of Air:
Air is a mixture of several gases.
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.
Some other gases like argon, neon, helium, krypton, hydrogen, zenon and methane are also present.
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.
A primary pollutant is an air pollutant emitted directly from a source.
A secondary pollutant is not directly emitted.
Primary pollutants are as follows:
Oxides of Sulphur
Oxides of Nitrogen
Oxides of Carbon
Particulate Matter and
Other primary pollutants
Secondary pollutants are as follows:
Ground Level Ozone
Smog2. Define earthquake and list out its effects.
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.
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.
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

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.
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.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.