Free Environment and Atmosphere MCQs with Answers

21. The phenomenon of Aurora Borealis, the display of red and green lights in northern hemisphere is due to radiations from____________ ?

• A. Ionosphere
• B. Troposphere
• C. Mesosphere
• D. Stratosphere
• E. None of these

Explanation: Aurora Borealis occurs when charged particles from the Sun excite gases in the upper atmosphere, mainly the ionosphere and thermosphere. These gases emit coloured light as they return to lower energy states.

22. Ozone layer prevents ______________ radiation from entering the atmosphere?

• A. Infra-red
• B. Ultraviolet
• C. X-rays
• D. Gamma rays
• E. None of these

Explanation: Stratospheric ozone absorbs much of the Sun's harmful ultraviolet radiation, especially UV-B and UV-C. It does not primarily block infrared, X-rays or gamma rays.

23. Sedimentary rocks are__________?

• A. Porous
• B. Hard
• C. Rough
• D. Brittle
• E. Volcanic

Explanation: Sedimentary rocks form from deposited particles that become compacted and cemented, leaving pores between grains in many cases. This porosity is a common feature, although it varies with compaction and cementation.

24. Which of the following atmospheric layers help in radio communication?

• A. Exosphere
• B. Ionosphere
• C. Troposphere
• D. Stratosphere
• E. Ozone layer

Explanation: The ionosphere contains charged particles that reflect or refract certain radio waves back toward Earth. This allows radio signals to travel beyond the horizon over long distances.

25. Monsoon is caused by____________________?

• A. Seasonal reversal of winds
• B. Revolution of earth
• C. Movement of clouds
• D. Rise in temperature
• E. Rain forests

Explanation: Monsoons result from seasonal differences in heating between land and sea, which reverse the prevailing wind direction. This wind reversal produces distinct wet and dry seasons.

26. Which of the following layers make radio transmission possible?

• A. Troposphere
• B. Ionosphere
• C. Mesosphere
• D. Stratosphere
• E. None of these

Explanation: The ionosphere contains charged particles that can reflect or refract certain radio waves back toward Earth, allowing signals to travel beyond the horizon. The lower atmospheric layers do not provide this main long-distance effect.

27. Hygrometer is used for measuring the ____________?

• A. Speed of sound
• B. Density of milk
• C. Humidity of air
• D. Specific gravity of liquids
• E. None of these

Explanation: A hygrometer measures the moisture content, or relative humidity, of air. Instruments measuring pressure, density or specific gravity serve different purposes.

28. One of the main function of the earth's ozone layer is to ?

• A. Prevent global warming
• B. Filter out ultraviolet rays
• C. Absorb pollution
• D. All of the above

Explanation: Stratospheric ozone absorbs much of the Sun’s harmful ultraviolet radiation, especially UV-B and UV-C. It is not correctly described as a general pollution absorber or a direct preventer of global warming.

29. Human population growth is greatest in developing countries because ?

• A. the birth rate is high in developing countries
• B. the death rate is high in developing countries.
• C. much of the population has already reached the child bearing age.
• D. most of the world's population lives in industrialized countries.Trying Interactive Physics Simulation Software

Explanation: Population growth is greatest where birth rates remain high while death rates have fallen because of improved sanitation, medicine and food supply. A large young population can further increase growth, but high birth rate is the main general reason given here.

30. One of the countries through which equator passes is___________?

• A. Kenya
• B. Malaysia
• C. Malta
• D. Pakistan

Explanation: The equator crosses Kenya in East Africa, as well as countries such as Ecuador, Brazil and Indonesia. Malaysia, Malta and Pakistan lie north of the equator.