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Decks by anahita (0)
Geography grade 71
GEOGRAPHY
CH 4- Greenhouse Effect and Global warming
I. Multiple Choice Questions
1. The type of radiation which is absorbed by the ozone layer is _________.
(a) infrared radiation
(b) visible lights
(c) ultraviolet radiation
(d) radio waves
2. Assertion (A): Research is essential for creating new technologies to lower greenhouse gas
emissions.
Reason (R): Developing innovative solutions is crucial for both mitigating the causes and
adapting to the consequences of climate change.
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
3. Which of the following practices can reduce global warming?
(a) Using personal vehicles for all travel needs.
(b) Buying standard household appliances regardless of energy efficiency.
(c) Replacing incandescent light bulbs with CFL bulbs.
(d) Leaving lights on when not in room.
4. Which of the following is directly released into atmosphere when using an aerosol
deodorant can?
(a) Carbon dioxide
(b) Chlorofluorocarbons
(c) Water vapour
(d) Sulphur dioxide
5. The greenhouse effect is NOT responsible for__________.
(a) trapping heat within the earth’s atmosphere
(b) maintaining a habitable average global temperature
(c) causing the daily cycle of day and night
(d) contributing to global warming
Std. 7
2025-2026
2
Short Answer Questions:
1. Explain the difference between each of the following pairs.
a) Ozone and CFCs
Ans. Ozone absorbs the ultraviolet rays that reach the earth. CFC is a compound containing
carbon, fluorine and chlorine that is harmful to the atmosphere.
b) Greenhouse and Global warming
Ans. The greenhouse effect takes place when the heat of the sun is absorbed by the earth and
radiated back into the atmosphere. Global warming is the increase in the average temperature
of the earth.
2. Why do we call carbon dioxide a greenhouse gas?
Ans. Carbon dioxide is called greenhouse gas because it absorbs the heat of the sun. It
prevents the heat from being reflected into the atmosphere.
3. What is responsible for causing a hole in the ozone layer?
Ans. Deforestation or cutting down of trees, burning of harmful fossil fuels and releasing of
CFCs are responsible for causing a hole in the ozone layer.
4. State the impact of global warming on ocean current.
Ans. Global warming could permanently alter the movement of ocean currents in the mid and
higher latitudes of Europe and Asia.
5. State the anthropogenic (human activities) causes of global warming.
Ans. i) deforestation
ii) factories belching smoke
iii) airplanes flying in the sky
iv) rapid destruction of forests for agriculture and industry
6. State the causes that lead to the increase in greenhouse gases.
Ans. i) increase in industries
ii) increase in deforestation
iii) increase in atmospheric pollution due to emissions from chimneys of factories.
iv) increase in natural disasters like floods, volcanic eruptions and earthquakes that
release large amounts of smoke, dust and gases into the atmosphere.
v) increase in the methane content of the atmosphere because of large scale cattle
rearing, since cattle release methane.
vi) expansion of cities and towns.
7. Mention at least two ways in which we can reduce the emission of greenhouse gases.
Ans. i) By switching to renewable energy sources and reducing deforestation.
ii) By building seawalls to protect coastal communities from rising sea levels,
developing drought resistant crops and improving early warning systems for extreme
weather events.
3
Picture Study
1. A) The ozone layer is present in the Stratosphere. What is the role of this ozone
layer?
Ans. i) The ozone layer protects the earth from the ultraviolet rays of the sun.
ii) It is essential to preserve life on earth.
iii) If exposed to ultraviolet rays, humans and animals can suffer sunburn, cataract,
hair loss, skin cancer and birth deformities.
iv) Plant growth may also be affected.
B) Mention the causes of the depletion of the ozone layer.
Ans. i) CFCs used in refrigerants and solvents used in industries.
ii) The chlorine from the CFCs in the atmosphere leads to the depletion of the ozone
layer in the atmosphere.
iii) Deforestation
iv) Burning harmful fossil fuels
2.
i). What is global warming?
Ans. The greenhouse gases in the atmosphere trap a part of the heat radiated back by the
earth, increasing its temperature. The increase in the earth’s temperature is called global
warming.
ii) How would global warming influence the Earth’s climate and weather patterns?
Ans.
• Global warming will worsen climate change, which will lead to food shortages.
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• Climate change will cause disturbances in weather patterns and lead to frequent
and heavy floods in some areas and some areas drought.
• Climate change will cause the melting of ice caps with huge chunks of ice bergs
several kilometers across breaking off from the mainland.
• Many forms of wildlife will be at risk due to climate change.
• There will be an increase in strong hurricanes, tornadoes, sudden floods, heat
waves, wildfires and other similar disasters.
• There will be an increase in desertification in many places leading to acute food
shortages.
• It can also cause changes in the flow of the ocean currents.
3. How can students like us help reduce global warming in our daily lives?
Students’ Response
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