Question

Which of the following pairs of gases is mainly responsible for greenhouse effect? [NEET (National) 2019]

(a) Oxygen and Nitrogen

(b) Nitrogen and Sulphur dioxide

(c) Carbon dioxide and Methane

(d) Ozone and Ammonia

Answer/Explanation

Ans. (c)

Greenhouse effect is mainly contributed by carbon dioxide $(60 \%)$ and methane (20\%) along with nitrous oxide, nitrogen dioxide and chlorofluorocarbons.
Greenhouse effect results in the rise in temperature of earth because greenhouse gases has the ability to trap the heat of solar radiations.

Question

Global warming can be controlled by [NEET 2013]

(a) Reducing deforestation, cutting down use of fossil fuel

(b) Reducing reforestation, increasing the use of fossil fuel

(c) Increasing deforestation, slowing down the growth of human population

(d) Increasing deforestation, reducing efficiency of energy usage

Answer/Explanation

Ans. (a)

Global warming can be controlled by reducing deforestation, cutting down use of fossil fuel, which results into reduction in the concentration of one of the greenhouse gas, i.e. $\mathrm{CO}_2$ in the atmosphere. The other ways of reducing global warming are slowing down the growth of human population, improving efficiency of energy usage and encouraging eco-friendly sustainable development.

Question

Which one of the following pairs of gases are the major cause of ‘Greenhouse effect? [CBSE AIPMT 2011]
(a) $\mathrm{CO}_2$ and $\mathrm{CO}$

(b) $\mathrm{CFCs}$ and $\mathrm{SO}_2$

(c) $\mathrm{CO}_2$ and $\mathrm{N}_2 \mathrm{O}$

(d) $\mathrm{CO}_2$ and $\mathrm{O}_3$

Answer/Explanation

Ans. (c)

The phenomenon of keeping the earth’s surface warm is due to the presence of certain gases in the atmosphere that are called greenhouse gases.
The name is based after a similar warmer interior in a glass-enclosed greenhouse where glass panels, $\mathrm{CO}_2$ and water vapour allow the solar radiations to enter but prevent the escape of long wave heat radiations. $\mathrm{CO}_2$ and $\mathrm{N}_2 \mathrm{O}$ are the major cause of ‘greenhouse effect’. $\mathrm{CO}_2$ contributes $60 \%$ of total global warming.$\mathrm{N}_2 \mathrm{O}$ contributes $6 \%$ to greenhouse effect.

Question

 The two gases making highest relative contribution to the greenhouse gases are [CBSE AIPMT 2010]

(a) $\mathrm{CO}_2$ and $\mathrm{CH}_4$

(b) $\mathrm{CH}_4$ and $\mathrm{NO}_2$

(c) $\mathrm{CFCs}$ and $\mathrm{N}_2 \mathrm{O}$

(d) $\mathrm{CO}_2$ and $\mathrm{N}_2 \mathrm{O}$

Answer/Explanation

Ans. (a)

The greenhouse effect is a naturally occurring phenomenon that is responsible for warming of earth’s surface and atmosphere. $\mathrm{CO}_2(60 \%)$ and $\mathrm{CH}_4(20 \%)$ are commonly known as greenhouse gases because they are responsible for the greenhouse effect, that ultimately leads to global warming.

Question

 Which one of the following is the correct percentage of the two (out of the total of four) greenhouse gases that contribute to the total global warming? [CBSE AIPMT 2008]

(a) $\mathrm{CFCs} 14 \%, \mathrm{CH}_4 20 \%$

(b) $\mathrm{CO}_2 40 \%, \mathrm{CFCs} 30 \%$

(c) $\mathrm{N}_2 \mathrm{O} 6 \%, \mathrm{CO}_2 86 \%$

(d) $\mathrm{CH}_4 20 \%, \mathrm{~N}_2 \mathrm{O} 18 \%$

Answer/Explanation

Ans. (a)

The percentage of various greenhouse gases that contribute to total global warming are $\mathrm{CO}_2$ (warming effect $60 \%$ ), $\mathrm{CH}_4(20 \%)$, CFCs $(14 \%)$ and nitrous oxide $\mathrm{N}_2 \mathrm{O}(6 \%)$.

Question

 Which one of the following pair is mismatched? [CBSE AIPMT 2005]

(a) Biomass burning – Release of $\mathrm{CO}_2$

(b) Fossil fuel burning – Release of $\mathrm{CO}_2$

(c) Nuclear power – Radioactive wastes

(d) Solar energy – Greenhouse effect

Answer/Explanation

Ans. (d)

From the following pair (d) is mismatched because solar energy does not cause greenhouse effect.

Question

 Greenhouse effect refers to [CBSE AIPMT 1999]

(a) production of cereals

(b) cooling of earth

(c) trapping of UV rays

(d) warming of earth

Answer/Explanation

Ans. (d)

Greenhouse effects refer to warming of earth due to increase in $\mathrm{CO}_2, \mathrm{CFCs}, \mathrm{SO}_2$ and other substances that disturbe the balance between the amount of energy received and that reflected back into the space.

Question

Warm ocean surge of the Peru current recurring every 5 to 8 year or so in the East Pacific of South America is widely known as [CBSE AIPMT 1998]

(a) Magnox

(b) Gull stream

(c) El Nino

(d) Aye Aye

Answer/Explanation

Ans. (c)

EL Nino is a warm ocean surge of Peru current (flowing North from Antarctica along the West coast of South America to South Equador, the West). It recurs every 5-8 year or so, in the East Pacific of South America.

Question

 Which important greenhouse gas, other than methane, is being produced from the agricultural fields? [CBSE AIPMT 1998]

(a) Arsine

(b) Sulphur dioxide

(c) Ammonia

(d) Nitrous oxide

Answer/Explanation

Ans. (d)

In addition to $\mathrm{CO}_2$, some other gases also contribute to greenhouse effect. These include ozone, CFCs, nitrous oxide $\mathrm{N}_2 \mathrm{O}$ and even methane $\left(\mathrm{CH}_4\right)$.
Nitrous oxide is produced by denitrifying bacteria acting on artificial fertilisers applied to poorly aerated soils.

Question

 If there was no $\mathrm{CO}_2$ in the earth’s atmosphere the temperature of earth’s surface would be [CBSE AIPMT 1998]

(a) same as present

(b) less than the present

(c) higher than the present

(d) dependent on the amount of oxygen in the atmosphere

Answer/Explanation

Ans. (b)

$\mathrm{CO}_2$ layer around earth surface acts as insulator and does not allow heat of the earth to escape into space thus keeping the earth warm. It is an important constituent of green house gases present in earth’s atmosphere. The percentage of $\mathrm{CO}_2$ in causing global warming is $60 \%$.

Question

 The major contributor of green-house gases to the atmosphere is [CBSE AIPMT 1996]

(a) Russia

(b) USA

(c) Germany

(d) Brazil

Answer/Explanation

Ans. (b)

The major contributor of greenhouse gases to the atmosphere is USA. 

Question

Green-house effect is warming due to [CBSE AIPMT 1991]
(a) infra-red rays reaching earth

(b) moisture layer in atmosphere

(c) increase in temperature due to increase in carbon dioxide concentration of atmosphere

(d) ozone layer of atmosphere

Answer/Explanation

Ans. (c)

Increase in $CO_2$ concentration forms a cover around the earth, this cover inhibits the earth’s radiation to go out of earth’s environment thus, increases global temperature. This increased temperature results in melting of snow from hill tops and poles.

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