Atmosphere

Tick the correct option

Question 1(a)

Temperature of the atmosphere decreases with height at the rate of about

1. 6.4°C per km
2. 4.6°C per km
3. 4.6°C per m
4. 4.6°C per cm

Answer

6.4°C per km

Question 1(b)

When temperature of the atmosphere rises, air ............... .

1. Contracts
2. Compresses
3. Expands
4. Dissipates

Answer

Expands

Question 1(c)

Air containing water vapour is ............... than dry air.

1. Denser
2. Lighter
3. Heavier
4. Thinner

Answer

Lighter

Question 1(d)

At what height is the troposphere above sea level?

1. 14 km
2. 16 km
3. 18 km
4. 12 km

Answer

14 km

Question 1(e)

The lowermost limit of this layer is tropopause

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere

Answer

Stratosphere

Question 1(f)

The atmospheric layer which reflects the low frequency radio waves but absorbs the medium and high frequency waves

1. Exosphere
2. Ionosphere
3. Thermosphere
4. Mesosphere

Answer

Ionosphere

Question 1(g)

The layer that protects us from the ultraviolet rays of the sun

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere

Answer

Stratosphere

Question 1(h)

Coral reefs are at times referred to as the

1. Tundra vegetation
2. Rainforests of the sea
3. Equatorial vegetation
4. Tidal reefs

Answer

Rainforests of the sea

Question 1(i)

The gas that accounts for nearly half of the greenhouse gases.

1. Nitrous oxide
2. Carbon monoxide
3. Carbon dioxide
4. Sulphur dioxide

Answer

Carbon dioxide

Question 1(j)

The Global Environmental Facility (GEF) was set up in which year?

1. 1990
2. 1991
3. 1992
4. 1993

Answer

1991

Question 1(k)

The increase in temperature of the earth due to air pollution

1. Climate change
2. Global warming
3. Greenhouse effect
4. Acidification

Answer

Global warming

Question 1(l)

Which is not a measure to prevent ozone depletion?

1. Increase private vehicle driving
2. Avoid using pesticides
3. Ban the use of dangerous nitrous oxide
4. Strict laws for rocket launches

Answer

Increase private vehicle driving

Question 1(m)

The atmospheric layer that lies just above stratosphere

1. Troposphere
2. Mesosphere
3. Ionosphere
4. Exosphere

Answer

Mesosphere

Question 1(n)

The layer that contains ozone

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere

Answer

Stratosphere

Question 1(o)

According to the report of ............... , 72 percent of global warming is contributed by carbon dioxide, methane and nitrous oxide

1. IPCC
2. CPII
3. PICC
4. CICP

Answer

IPCC

Exercise

Question 2

Fill in the blanks:

(a) ............... coming from the sun penetrates the atmosphere and is absorbed by the earth.

(b) Concentration of greenhouse gases has risen rapidly due to ............... .

(c) The oceans serve as a ............... for carbon dioxide.

(d) The degree at which water vapour is present in the air is called ............... .

(e) The ozone layer lies in the ............... between 16 and 50 km above the earth’s surface.

(f) Many ............... spray cans contain harmful chemicals called chlorofluorocarbons (CFCs).

Answer

(a) Ultraviolet radiation coming from the sun penetrates the atmosphere and is absorbed by the earth.

(b) Concentration of greenhouse gases has risen rapidly due to human activities

(c) The oceans serve as a sink for carbon dioxide.

(d) The degree at which water vapour is present in the air is called humidity

(e) The ozone layer lies in the stratosphere between 16 and 50 km above the earth’s surface.

(f) Many aerosol spray cans contain harmful chemicals called chlorofluorocarbons (CFCs).

Question 3

Answer in one word:

(a) Gases used in some air-conditioners, refrigerators and spray-cans that can destroy ozone and trap the heat in the atmosphere.

(b) The outermost layer of the atmosphere that fades into outer space.

(c) The increase in the temperature of the earth due to air pollution.

(d) A form of oxygen that protects life from the ultraviolet rays of the sun.

Answer

(a) Chlorofluorocarbons (CFCs).

(b) Exosphere

(c) Global warming

(d) Ozone

Question 4(i)

State the major effects of climate change.

Answer

Following are the major effects of climate change:

1. Changes in rainfall patterns.
2. Increased frequency of extreme weather like flash flood, storm and heat wave.
3. Rise in sea level due to melting of polar ice.
4. Increased frequency of tropical cyclones.

Question 4(ii)

What is greenhouse effect? How does it lead to global warming?

Answer

The Earth's atmosphere contains gases such as carbon dioxide, methane, nitrous oxide (N₂O) etc. that allow the near infrared rays from the Sun to penetrate the Earth but do not allow the heat radiated by the heated Earth to penetrate back into space, thus, preventing the earth from becoming too cold at night. This phenomenon is known as greenhouse effect.
Due to the increase in the concentration of greenhouse in the atmosphere by human activities, Earth is warming up and there is a rise in the mean global temperature to a level where it affects the life on earth. In this way, greenhouse effect is leading to global warming.

Question 4(iii)

Name the major greenhouse gases and their sources.

Answer

The major greenhouse gases and their sources are:

Question 4(iv)

How does global warming cause spread of diseases?

Answer

Increased heat waves due to global warming can cause heat stroke and hyperthermia. Extreme heat is also linked to low quality sleep and acute kidney injury.
Extreme weather events, such as cyclones, floods and droughts caused by global warming can compromise access to clean water and sanitation, creating conditions conducive to the spread of waterborne and vector-borne diseases.

Question 4(v)

Where is ozone layer? Why is it getting depleted?

Answer

The ozone layer lies in the stratosphere, between 16 and 50 km above the earth’s surface.
Certain chemicals like CFCs (chlorofluorocarbons) cause ozone break down and thinning of the layer. Another cause of ozone depletion is the emission of green house gases due to burning of fossil fuels.

Question 4(vi)

How is ozone useful in the stratosphere?

Answer

Ozone layer lies in the stratosphere between 20-30 km. It is a major factor making life possible on earth. It absorbs most of the ultra violet radiation coming from the Sun. It protects the flora and fauna present on earth from the harmful effects of ultra violet radiation. It protects us from diseases like cancer and other skin ailments which are caused due to exposure to ultra violet radiations.

Question 4(vii)

What are chlorofluorocarbons? Name their sources.

Answer

CFCs (Chlorofluorocarbons) are man-made greenhouse gases which come from refrigerators and foam.
The sources of CFCs are coolants in refrigerators and ACs, aerosol sprays and blowing agents in foam.

Question 4(viii)

Ozone depletion and climate change are serious threats to the very survival of human beings. What are the measures taken by various countries to mitigate the problem?

Answer

International efforts to control these problems are as follows:

1. The United Nations framework convention on climate change (UNFCCC) — In the convention, it was agreed that the future global warming should be limited to below 2°C relative to the preindustrial level.
2. The Kyoto protocol — In this protocol countries agreed to cut the greenhouse gas emissions by 5.4 per cent.
3. The Global Environmental Facility (GEF) — Its main objectives are reduction of greenhouse effect and reduction of ozone layer depletion.

Question 4(ix)

State the objectives of Global Environmental Facility (GEF).

Answer

The main objectives of GEF were —

1. Reduction of greenhouse effect in the atmosphere.
2. Protection of biological diversity.
3. Protection of international waters.
4. Reduction of ozone layer depletion.

Question 4(x)

State the effect of global warming on flora and fauna of the earth.

Answer

Plants and animals react to warmer temperatures by moving to higher elevations and latitudes. Species loss and endangerment is rising along with global temperatures. As many as 30 per cent of plants and animals today risk extinction by 2050, if average temperatures rise by 6.4°C then 18% of all insect species would be lost by 2100. Such extinctions will be due to loss of habitat through desertification, deforestation, ocean warming and global warming.

Question 4(xi)

State the effects of ozone depletion on the earth.

Answer

Effects of ozone depletion:

1. As the ozone layer is destroyed or becomes very thin, it fails to absorb the ultraviolet radiation.
2. As a result, an increasing amount of ultraviolet radiation reaches the earth and causes damage to plant life, human beings and marine life.
3. Skin cancer is caused and the incidence of cataract also increases as a result of ozone depletion in the atmosphere. The body is exposed to infectious diseases.
4. Planktons, which are the very foundation of the vast oceanic food chain, are also killed.

Question 4(xii)

Which gas is released from the use of chemical fertilizers and pesticides? In what way does it affect the atmosphere?

Answer

Nitrous oxide is released from the use of chemical fertilizers and pesticides.
Nitrous oxide is a greenhouse gas that causes greenhouse effect and contributes to global warming.

Question 4(xiii)

State the ways to reduce global warming.

Answer

Some of the ways to reduce global warming are:

1. The conservation of forests.
2. Reduce industrial pollution.
3. Prevent the emission of greenhouse gases.
4. Use public transport and car-pooling.
5. Reduce, reuse and recycle products.
6. Energy conservation.
7. More use of renewable energy.

Question 4(xiv)

How can we prevent ozone depletion?

Answer

We can prevent ozone depletion in following ways:

1. Limit private vehicle driving.
2. Use eco-friendly household cleaning products.
3. Avoid using pesticides.
4. Ban the use of dangerous nitrous oxide.
5. Develop stringent regulations for rocket launches.