Question

Gases mainly responsible for the green-house effect are
A. $C{O_2}$ and $CO$
B. $CO$ and ${H_2}$
C. $C{O_2}$ and ${N_2}O$
D. $C{O_2}$ and $S{O_2}$

Answer 1

Hint: The green-house effect is caused by greenhouse gases that are present in abundance in the environment. The gases can either be natural or artificial. They trap the sun’s energy which leads to the warming of the earth's surface and the atmosphere. The major contributors to the green-house effect are gases containing carbon and nitrogen.

Complete answer:
Carbon dioxide and nitrous oxide are gases that are mainly responsible for the green-house effect. Human activities have led to an increase in the amount of these gases, which has significantly enhanced the green-house effect. Other than $C{O_2}$ and ${N_2}O$ , there are various green-house gases – methane, water vapour, ozone, and artificial chemicals known as Chlorofluorocarbons.

Greenhouse effect:
- When the sun rays enter the earth’s atmosphere, some of the energy is reflected back. The rest of the energy is trapped by greenhouse gases like water vapor, carbon dioxide, methane, nitrous oxide, ozone, and Chlorofluorocarbons. This results in the warming of the earth’s surface and the lowest layer of the atmosphere (troposphere).
- The green-house effect is important as it maintains a level of temperature on earth without which life would be impossible.
- This effect becomes harmful when the amount of gases in the atmosphere increases. This leads to the continuous warming up of the earth and atmosphere. This has an immense impact on climate and weather.

Hence, the correct answer is option (C).

Note: Various human activities such as the burning of fossil fuels, use of fertilizers, deforestation, etc. have led to the rise in greenhouse gases
- $C{O_2}$ generates around $55\% $ of the human-induced greenhouse effect.
- ${N_2}O$ generates approximately $5\% $ of the human-induced greenhouse effect.
- Methane contributes a little over $15\% $ .
- Ozone generates approximately $10\% $ of the induced gases.