VIII - SOCIAL SCIENCE - HAZARDS - EVALUATION -QUESTION - ANSWERS

 

HAZARDS

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% 

Ans: a) 78.09 %

2. Tsunami in Indian Ocean took place in the year _________. 

a) 1990 

b) 2004 

c) 2005 

d) 2008 

Ans: b) 2004

3. The word Tsunami is derived from __________ language. 

a) Hindi 

b) French 

c) Japanese 

d) German

Ans: c) Japanese

4. The example of surface water is 

a) Artesian well 

b) Groundwater

c) Subsurface water 

d) Lake

Ans: d) Lake

5. Event that occurs due to the failure of monsoons.

a) Condensation 

b) Drought

c) Evaporation 

d) Precipitation

Ans: b) Drought

II Fill in the blanks

1. Hazards may lead to_______.

Ans: Disaster

2. Landslide is an example of _______ hazard.

Ans: Natural

3. On the basis of origin, hazard can be grouped into _______ categories.

Ans: 8

4. Terrorism is an example of _______ hazard.

Ans: Human - made

5. Oxides of Nitrogen are _______pollutants which affects the human beings.

Ans.: Primary

6. Chernobyl nuclear accident took place in _______ year.

Ans: 1986

III Match the following

List I	List II
Primary pollutant	Terrorism
Hazardous waste	Tsunami
Earthquake	Outdated drugs
Meteorological drought	Oxides of Sulphur
Human induced hazard	Reduction in rainfall

Ans:

List I	List II
Primary pollutant	Oxides of Sulphur
Hazardous waste	Outdated drugs
Earthquake	Tsunami
Meteorological drought	Reduction in rainfall
Human induced hazard	Terrorism

IV  Answer briefly

1. Define ‘hazard’.

Hazards are defined as the phenomena that pose a threat to people, structures or economic assets and which may cause disaster.

2. What are the major types of hazards?

There are three types of hazards namely natural hazards,human-made hazards and 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.

The major flood prone areas in India are. 

• Gangetic plains covering the states of Punjab, Haryana, Uttar Pradesh, North Bihar, West Bengal and Brahmaputra valley are the major flood prone areas in north and northeast India. 

• Coastal Andhra Pradesh, Odisha and southern Gujarat are the other regions which are also prone to flood often.

5. Mention the types of drought.

The drought can be classified into three major types;

•  Meteorological drought

•  Hydrological drought

• Agricultural drought

6. Why should not we construct houses at foothill areas?

Foothills areas are highly prone to landslides, so we should not construct houses in foothill areas.

V Distinguish between

1. Hazards and disasters.

Hazards	Disasters
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.	A disaster is a hazardous event that occurs over a limited time span in a defined area and causes great damage to property/ loss of life, also needs assistance from others

2. Natural hazard and human-made hazard.

Natural hazards	Human-made hazards
These are the results of natural processes and man has no role to play in such hazards.	These are caused by undesirable activities of humans. It can be the result of an accident, such as an industrial chemical leak or oil spill, or an intentional act. Such hazards can disturb the safety health, welfare of people and cause damage or destruction to property.
The main examples of natural hazards are earthquakes, floods, cyclonic storms, droughts, landslides, tsunamis and volcanic eruptions.	The following are the examples of human-made hazards. They are explosions, hazardous wastes, pollution of air, water and land, dam failures, wars or civil conflicts and terrorism.

3. Flood and drought.

Floods	Droughts
Flood is an event in which a part of the earth’s surface gets inundated.	Any lack of water to satisfy the normal needs of agriculture, livestock, industry or human population may be termed as a drought.
Heavy rainfall and large waves in seas are the common causes of flood.	Droughts in India occur in the event of a failure of monsoon

4. Earthquake and Tsunami.

Earthquake	Tsunami
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.	Tsunami refers to huge ocean waves caused by an earthquake, landslide or volcanic eruption.
Earthquake prone regions of the country have been identified on the basis of scientific inputs relating to seismicity, earthquakes occurred in the past and tectonic setup of the region	It is generally noticed in the coastal regions and travel between 640 and 960 km/h. Tsunami pose serious danger to the inhabitants of the coastal areas.

VI Answer in a paragraph

1. Write an essay on air pollution.

• Air is a mixture of several gases. 

• The main gases are nitrogen (78.09%) for forming products such as, fertilisers 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, ozone, zenon and methane are also present.

• Besides, water vapour and dust particles make their presence felt in one way or the other. 

Air pollution is the contamination of the indoor or outdoor air by a range of gases and solids that modify its natural characteristics and percentage. 

Air pollutants can be categorised into primary and secondary pollutants. 

A  primary pollutant  is an air pollutant emitted directly from a source. 

A  secondary pollutant  is not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere. 

Primary Pollutants 

i) Oxides of Sulphur

ii) Oxides of Nitrogen

iii) Oxides of Carbon 

iv) Particulate Matter 

v) Other Primary Pollutants

Secondary Pollutants 

i) Ground Level Ozone 

ii) Smog

2. 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 occurred in the past and tectonic setup of the region. 

• Based on these inputs, 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).

 

3. Give a detailed explanation on the causes of landslides.

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

• Landslides are generally sudden and infrequent. 

• Presence of steep slope and heavy rainfall are the major causes of landslides. Weak ground structure, deforestation, earthquakes, volcanic eruptions, mining, construction of roads and railways over the mountains are the other causes of landslides.

• About 15% of India’s landmass is prone to landslide hazard. 

• Landslides are very common along the steep slopes of the Himalayas, the Western Ghats and along the river valleys. In Tamil Nadu, Kodaikanal (Dindigul district) and Ooty (The Nilgiris district) are frequently affected by landslides.

4. Elaborately discuss the effects of water pollution

• Water pollution may be defined as alteration in the physical, chemical and biological characteristics of water, which may cause harmful effects in human and aquatic life 

• In India, water pollution has been taking place on a large scale and since a long period. 

• Both surface and groundwater bodies are polluted to a great extent. 

The major causes of water pollution in India are:

 i) Urbanisation

ii) Industrial effluents 

iii) Sewages 

iv) Agricultural runoff and improper agricultural practices 

v) Seawater intrusion 

vi)Solid wastes

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