75 RAS Prelims MCQs on environmental issues cover desertification, deforestation, global warming, climate agreements and the ozone layer. Greenhouse gases, the IPCC, the Montreal Protocol, the Kigali Amendment, the Paris Agreement, the Great Green Wall and desertification in Rajasthan and India are asked as facts, dates and statements.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Q51. Given below are two statements, one labelled as Assertion (A) and the other as Reason (R): Assertion (A): Widespread deforestation in the Amazon basin can lead to a significant decline in regional rainfall. Reason (R): Deforestation reduces the number of trees available to undergo evapotranspiration, thereby cutting off a crucial source of moisture for the atmosphere. Select the correct answer from the codes given below:
Explanation
Trees in the Amazon basin play a critical role in the regional water cycle by recycling moisture through evapotranspiration. This process supplies a large portion of the water needed for rainfall in the area. When forests are removed, this moisture source is significantly reduced, leading to a decline in precipitation. This feedback loop can potentially trigger a transition toward drier, savanna-like conditions.
Q52. Which of the following statements regarding greenhouse gases is INCORRECT?
Explanation
Carbon dioxide is the main gas emitted by humans, and methane is more potent despite its shorter life. However, nitrous oxide emissions are primarily linked to agricultural activities, specifically the use of synthetic nitrogen fertilizers. Refrigeration systems are historically associated with ozone-depleting substances like chlorofluorocarbons and modern hydrofluorocarbons. Correctly identifying these sources is vital for designing effective environmental policies and emission reductions.
Q53. In the context of the Sahel region desertification, which practice is recognized as the major historical anthropogenic driver of land degradation?
Explanation
While climate variability plays a significant role in the Sahel, overgrazing has historically been the primary human driver of land degradation. Excessive grazing by livestock removes protective vegetation, leaving the soil exposed to erosion by wind and rain. This reduces the land’s productivity and ability to recover, leading to desertification. Addressing this requires managing livestock densities and promoting sustainable grazing practices.
Q54. Consider the following statements regarding ozone depletion: I. Ozone depletion is most severe over the Arctic region compared to the Antarctic. II. Polar stratospheric clouds play a crucial role in providing a surface for chemical reactions that lead to ozone destruction. III. The Montreal Protocol has been universally ratified to phase out ozone-depleting substances. IV. The ozone hole peaks during the southern hemisphere’s spring season. Which of the above statement(s) is/are correct?
Explanation
Ozone depletion is most severe over the Antarctic due to unique meteorological conditions like the polar vortex. Polar stratospheric clouds provide the necessary surfaces for the chemical reactions that release ozone-destroying chlorine. The Montreal Protocol is a successful, universally ratified treaty that phases out these harmful substances. The Antarctic ozone hole typically reaches its maximum size during the southern hemisphere’s spring season.
Q55. Identify the odd one out concerning major natural carbon sinks on Earth.
Explanation
Natural carbon sinks, such as oceans, intact forests, and peatlands, absorb and store more carbon dioxide than they release. These ecosystems are vital for regulating the global climate. In contrast, urban areas are significant sources of carbon emissions due to energy use and transportation. The "urban heat island" effect refers to localized warming in cities and is not a mechanism for carbon sequestration.
Q56. Increased levels of dissolved carbon dioxide in the Earth’s oceans primarily lead to which chemical effect?
Explanation
When the oceans absorb increased levels of atmospheric carbon dioxide, the gas reacts with seawater to form carbonic acid. This process increases the concentration of hydrogen ions, leading to a decrease in the water’s pH level. This phenomenon, known as ocean acidification, makes it more difficult for marine organisms like corals and shellfish to build and maintain their calcium carbonate structures.
Q57. Which of the following pairs concerning the indicators of desertification is correctly matched?
Explanation
Desertification can be monitored using various indicators. A decline in the groundwater table is a key physical indicator reflecting water scarcity. Changes in plant species composition are biological indicators, while soil salinity is a chemical indicator. Social indicators involve human impacts, such as the outmigration of populations from degraded lands. Accurately categorizing these indicators is essential for effective environmental monitoring and policy responses.
Q58. The ‘Suess Effect’ is often cited as evidence of anthropogenic climate change. What does this effect specifically demonstrate?
Explanation
The Suess Effect is the change in the atmospheric carbon isotope ratios caused by burning fossil fuels, which contain no carbon-14. It shows that the extra CO2 comes from fossil fuels.
Q59. Match List-I with List-II concerning environmental terms:
Action
Definition
A. Afforestation
i. The clearing of forest areas for non-forest land uses
B. Reforestation
ii. Land degradation in arid, semi-arid, and dry sub-humid areas
C. Deforestation
iii. Planting trees in an area that was not previously forested
D. Desertification
iv. Replanting trees in an area where a forest was recently cleared
Select the correct answer from the codes given below:
Explanation
Afforestation is planting trees where there was no forest, reforestation is replanting where forest was recently cleared, deforestation is clearing forest for other uses and desertification is land degradation in dry areas. This gives A-iii, B-iv, C-i, D-ii.
Q60. The Great Green Wall initiative is fundamentally associated with which continent?
Explanation
The Great Green Wall is an African initiative to plant a belt of trees and restore land across the Sahel, south of the Sahara, in order to fight desertification.
Answer key for these questions
Q
Correct answer
51
(a) Both A and R are true and R is the correct explanation of A.
52
(c) Nitrous oxide emissions are predominantly associated with the cooling systems of older refrigerators.
53
(b) Overgrazing by nomadic livestock herds
54
(b) II, III and IV
55
(a) Expanding urban heat islands
56
(c) A decrease in ocean pH, causing ocean acidification
57
(a) Physical indicator - Decline in groundwater table
58
(d) Change in atmospheric carbon isotope ratios, proving the CO 2 is from fossil fuels.
59
(a) A-iii, B-iv, C-i, D-ii
60
(c) Africa
Key facts from Environmental Issues: Desertification, Deforestation, Climate Change and Ozone Depletion
Water vapour is the most abundant greenhouse gas, and the ozone layer lies in the stratosphere.
The IPCC was established in 1988; the order is Montreal Protocol, IPCC, UNFCCC, Paris Agreement.
The Kigali Amendment of 2016 targets the phase-down of hydrofluorocarbons (HFCs).
The Amazon Basin has the highest absolute rate of tropical deforestation and holds about half the world’s remaining tropical rainforest.
The Great Green Wall is an African initiative; about 30 per cent of India’s area is undergoing land degradation or desertification.
In the Thar desert, wind erosion and shifting sand dunes are the most widespread problem; poor drainage in irrigated dry land causes salinisation.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Environmental Issues: Desertification, Deforestation, Climate Change and Ozone Depletion?
This page has 75 practice MCQs on Environmental Issues: Desertification, Deforestation, Climate Change and Ozone Depletion (World Geography). Each has the correct answer, and most have an explanation.
When was the IPCC established?
In 1988, by the World Meteorological Organization and the United Nations Environment Programme. It assesses the science of climate change and its reports guide the climate negotiations, including the Paris Agreement.
What does the Kigali Amendment target?
The phase-down of hydrofluorocarbons (HFCs), which are strong greenhouse gases used in cooling. It was adopted in 2016 as an amendment to the Montreal Protocol, which was originally made to protect the ozone layer.
What is the Great Green Wall?
An African initiative to restore land and plant a belt of trees across the Sahel, south of the Sahara. Its aim is to fight desertification, improve food security and support local communities.
