Environment and Sustainable Development (Environment and Ecology)

Total Questions: 95

11. Which of the following does not add the carbon dioxide to carbon cycle on the planet Earth? [U.P.P.C.S. (Mains) 2012]

Correct Answer: (b) Photosynthesis
Solution:While respiration, the decay of organic matter, and volcanic action all release carbon dioxide () into the atmosphere, photosynthesis is the process by which plants and other organisms use sunlight to synthesize foods from and water. This process actively removes from the atmosphere, playing a crucial role in balancing the carbon cycle.

12. The main role of solar radiation is in - [U.P. Lower Sub. (Spl.) (Pre) 2004, U.P.P.C.S. (Pre) 2000]

Correct Answer: (c) Water cycle
Solution:Solar radiation, or energy from the sun, is the primary driving force behind the water cycle. The sun's heat causes water to evaporate from oceans, lakes, and rivers, converting it into a vapor.

This vapor rises and eventually condenses to form clouds, which then release the water back to the Earth as precipitation (rain, snow, etc.). Without solar energy, the continuous movement of water on, above, and below the surface of the Earth would not be possible.

13. Amount of rain depends on : [U.P.P.C.S. (Pre) 2017]

Correct Answer: (b) Humidity in atmosphere
Solution:Humidity refers to the amount of water vapor present in the air. The amount of rain that falls is directly dependent on the humidity. When air is highly humid, it contains a large amount of water vapor.

As this humid air cools, the water vapor condenses into liquid droplets or ice crystals, forming clouds. When these droplets become heavy enough, they fall to Earth as precipitation. Thus, a high level of humidity is a prerequisite for significant rainfall.

14. Many transplanted seedlings do not grow because : [I.A.S. (Pre) 2013]

Correct Answer: (c) Most of the root hairs are lost during transportation
Solution:Root hairs are tiny, delicate extensions of a plant's root system that are crucial for absorbing water and nutrients from the soil. When a seedling is transplanted, these root hairs are very easily damaged or torn off.

Without a sufficient number of root hairs, the plant cannot absorb the water and minerals it needs to survive, leading to wilting and eventual death. The loss of these vital structures is the primary reason for transplant shock.

15. What is the thin layer of gases around the earth called? [44ᵗʰ B.P.S.C. (Pre) 2000]

Correct Answer: (c) Atmosphere
Solution:The atmosphere is the layer of gases surrounding the Earth, held in place by gravity. It is essential for life, as it contains oxygen for respiration and protects the planet from harmful solar radiation.

The biosphere is the part of the Earth where life exists, the hydrosphere is all the water on the planet, and a water particle is a single molecule of water.

16. Air is a/an: [39ᵗʰ B.P.S.C. (Pre) 1994]

Correct Answer: (c) Mixture
Solution:Air is a mixture of different gases. It is composed primarily of nitrogen (about 78%), oxygen (about 21%), and small amounts of other gases like argon, carbon dioxide, and neon.

These gases are not chemically bonded together; they are simply mixed in the same space. Because the components of air are not fixed in a specific chemical ratio, it is considered a mixture rather than a compound or an element.

17. Which one of the following Noble Gases is not present in the air? [U.P.P.C.S. (Pre) 2005]

Correct Answer: (c) Radon
Solution:Noble gases such as helium, neon, argon, krypton, and xenon are all naturally present in the atmosphere in very small, trace amounts.

Radon, however, is a radioactive noble gas produced by the radioactive decay of uranium in the Earth's crust. It is not a stable component of the atmosphere and its presence is highly localized and transient, usually dissipating quickly. Thus, it is not considered to be a constituent of air.

18. Percentage of Nitrogen in dry air - [M.P.P.C.S. (Pre) 1990]

Correct Answer: (d) 78%
Solution:Nitrogen () is the most abundant gas in the Earth's atmosphere, making up approximately 78% of dry air by volume. While oxygen is essential for life, its concentration is much lower at about 21%. The remaining 1% consists of other gases, including argon, carbon dioxide, and various trace gases.

19. In the atmosphere, the highest percentage is of: [Uttrakhand U.D.A./LDA (Mains) 2007]

Correct Answer: (c) Nitrogen
Solution:The dry air/atmosphere around us is a mixture of gases, mainly Nitrogen and Oxygen, but containing much smaller amounts of water vapour, Argon, and Carbon Dioxide and very small amounts of other gases.
GasPercentage 
Nitrogen (N2)78.08 %
Oxygen (O2)20.95%
Argon (Ar)0.93%
Carbon Dioxide (CO2)0.036%
Neon (Ne)0.002%
Helium (He)0.0005%
Krypton0.001%
Xenon0.00009%
Hydrogen0.00005%

20. The highest percentage of gas in the air is - [41st B.P.S.C. (Pre) 1996]

Correct Answer: (d) Nitrogen
Solution:The dry air/atmosphere around us is a mixture of gases, mainly Nitrogen and Oxygen, but containing much smaller amounts of water vapour, Argon, and Carbon Dioxide and very small amounts of other gases.
GasPercentage 
Nitrogen (N2)78.08 %
Oxygen (O2)20.95%
Argon (Ar)0.93%
Carbon Dioxide (CO2)0.036%
Neon (Ne)0.002%
Helium (He)0.0005%
Krypton0.001%
Xenon0.00009%
Hydrogen0.00005%