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100 questions in this collection · Page 3 of 10
Question 21 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding Radioactive Wastes:
I. Nuclear energy was initially considered a non-polluting way of generating electricity. II. Serious accidental leakages of radiation occurred at Three Mile Island and Chernobyl. III. The standard safe disposal method involves storing radioactive waste in shielded containers buried 50 meters deep within rocks.
Which of the statements given above are correct?
Initially, nuclear energy was considered a non-polluting source of electricity. Radiation accidents occurred at Three Mile Island and Chernobyl. Radioactive wastes are recommended to be buried in shielded containers about 500 metres below the Earth's surface, not 50 metres.
Question 22 of 100
📘 CLASS XII
Environmental Issues
The greenhouse effect is described in the following statements:
I. Without the greenhouse effect, the average temperature of the Earth would be -18°C rather than the present average of 15°C. II. Carbon dioxide (CO2) and methane (CH4) are the two main greenhouse gases. III. Nitrous oxide (N2O) contributes 14%, and CFCs contribute 6% to total global warming. IV. During the past century, the Earth's temperature increased by about 0.6°C, mostly during the last three decades.
Which of the statements given above are correct?
Statement III is incorrect because the contributions are approximately: CO2 60%, CH4 20%, CFCs 14%, and N2O 6%. Statements I, II and IV are correct.
Question 23 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the consequences of Global Warming:
I. Global warming leads to odd climatic changes, such as the El Nino effect. II. It is causing increased melting of polar ice caps and Himalayan snow caps. III. Over decades, this melting will result in a rise in sea level, which threatens to submerge coastal areas. IV. Global warming affects temperatures but has absolutely no impact on rainfall patterns.
Which of the statements given above are correct?
Global warming contributes to climatic changes including El Nino effects, melting of polar and Himalayan ice, and sea-level rise. It also affects rainfall patterns, making Statement IV incorrect.
Question 24 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding Ozone in different layers of the atmosphere:
I. 'Bad' ozone is formed in the lower atmosphere (troposphere) and harms plants and animals. II. 'Good' ozone is found in the upper atmosphere (stratosphere) and acts as a shield absorbing harmful UV rays. III. The thickness of ozone in a column of air from the ground to the top of the atmosphere is measured in Dobson Units (DU).
Which of the statements given above are correct?
All statements are correct. Tropospheric ozone is a harmful pollutant, whereas stratospheric ozone protects life by absorbing harmful ultraviolet radiation. Ozone thickness is measured in Dobson Units (DU).
Question 25 of 100
📘 CLASS XII
Environmental Issues
Analyze the chemical process of Stratospheric Ozone Depletion:
I. Chlorofluorocarbons (CFCs) discharged in the lower atmosphere move upward and reach the stratosphere. II. In the stratosphere, UV rays act on CFCs to release chlorine atoms. III. Chlorine atoms react with ozone to release oxygen, and are completely consumed during this process. IV. The ozone hole over Antarctica develops each year between late August and early October.
Which of the statements given above are correct?
UV radiation breaks down CFCs in the stratosphere, releasing chlorine atoms. Chlorine acts as a catalyst and is not consumed during ozone destruction. The Antarctic ozone hole develops between late August and early October.
Question 26 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the global loss of forests:
I. According to estimates, almost 40 percent of forests have been lost in the tropics. II. In comparison, only about 1 percent of forests have been lost in the temperate region. III. The scenario of deforestation is especially grim in temperate zones compared to tropical zones. IV. Deforestation is defined as the conversion of forested areas to non-forested ones.
Which of the statements given above are correct?
Almost 40% of tropical forests have been lost compared with about 1% in temperate regions. Deforestation refers to conversion of forested land into non-forested areas. Statement III is incorrect because the situation is much more severe in tropical regions.
Question 27 of 100
📘 CLASS XII
Environmental Issues
With reference to the historical forest cover of India, read the following statements:
I. At the beginning of the twentieth century, forests covered about 30 percent of the land of India. II. By the end of the twentieth century, forest cover had shrunk to 19.4 percent. III. The National Forest Policy (1988) of India recommends 33 percent forest cover for the plains. IV. The National Forest Policy (1988) recommends 67 percent forest cover for the hills.
Which of the statements given above are correct?
At the beginning of the twentieth century, forests covered about 30% of India. By the end of the century, forest cover had reduced to about 21.54%, not 19.4%. The National Forest Policy (1988) recommends 33% forest cover for plains and 67% for hills.
Question 28 of 100
📘 CLASS XII
Environmental Issues
Regarding "Slash and Burn" agriculture or Jhum cultivation, analyze the following statements:
I. It is commonly practiced in the north-eastern states of India. II. Farmers cut down forest trees and burn the plant remains, using the ash as a fertilizer. III. The land is used for farming or cattle grazing, and then immediately replanted the next season with fast-growing timber. IV. With increasing population and repeated cultivation, the recovery phase has been done away with, leading to deforestation.
Which of the statements given above are correct?
Jhum cultivation is practiced mainly in north-eastern India. Forest vegetation is cut and burnt, and the ash acts as fertilizer. Traditionally, land was left fallow for natural recovery rather than immediately replanted. Due to population pressure, the recovery period has greatly reduced, causing deforestation.
Question 29 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the consequences of deforestation:
I. It leads to an enhanced carbon dioxide concentration in the atmosphere because trees that hold carbon in their biomass are lost. II. Deforestation causes loss of biodiversity due to habitat destruction. III. It stabilizes the hydrologic cycle and prevents soil erosion in hilly terrains. IV. Deforestation may lead to desertification in extreme cases.
Which of the statements given above are correct?
Deforestation increases atmospheric CO2, destroys habitats, and may ultimately cause desertification. It actually disturbs the hydrologic cycle and accelerates soil erosion, making Statement III incorrect.
Question 30 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding Amrita Devi Bishnoi's forest conservation efforts:
I. In 1731, the king of Udaipur asked his ministers to arrange wood for a new palace. II. Amrita Devi Bishnoi showed exemplary courage by hugging a tree to protect it from being cut down. III. Her three daughters and hundreds of other Bishnois sacrificed their lives saving trees. IV. The Government of India has instituted the Amrita Devi Bishnoi Wildlife Protection Award for rural individuals or communities.
Which of the statements given above are correct?
The incident occurred under the orders of the King of Jodhpur, not Udaipur. Amrita Devi, her daughters, and hundreds of Bishnois sacrificed their lives protecting trees. The Government of India instituted the Amrita Devi Bishnoi Wildlife Protection Award in her honour.