Free Environment and Atmosphere MCQs with Answers

211. Radon is___________?

• A. germon radio
• B. radio active gas
• C. artificial fibre
• D. an explosive

Explanation: Radon is a naturally occurring radioactive noble gas produced during the decay of uranium in rocks and soil. It can accumulate indoors and increase lung-cancer risk after prolonged exposure.

212. What Color does chlorophyll not absorb?

• A. Red
• B. Blue
• C. Green
• D. Yellow

Explanation: Chlorophyll absorbs mainly blue-violet and red light but reflects green light, which is why leaves appear green. Green is therefore the standard answer for the colour it does not effectively absorb.

213. For water purification, we use?

• A. Chlorine
• B. Bromine
• C. Plants
• D. Young man

Explanation: Chlorine is added to water to kill many disease-causing microorganisms during disinfection. Bromine can disinfect in special applications, but chlorine is the standard agent used in public water purification.

214. Air contains volume of carbon dioxide approximately?

• A. 3%
• B. 33%
• C. 0.3%
• D. 0.03%

Explanation: Traditional atmospheric composition tables give carbon dioxide as about 0.03% by volume, although the present value is slightly above 0.04%.

215. During a total solar eclipse there is most likely to be_____________?

• A. A decrease in the rate of photosynthesis
• B. An increase in the rate of photosynthesis
• C. A decrease in the rate of respiration
• D. No effect on either photosynthesis or respiration

Explanation: A total solar eclipse temporarily reduces sunlight, so the light-dependent reactions of photosynthesis slow down. Respiration does not stop, making decreased photosynthesis the best answer.

216. What is the world's warmest Sea?

• A. Red Sea
• B. Mediterranean Sea
• C. Caspian Sea
• D. Arabian Sea

Explanation: The Red Sea is commonly regarded as the world's warmest sea because it lies in a hot, arid region and has limited exchange with cooler ocean water. Its high evaporation also makes its water notably saline.

217. What is the warmest Ocean?

• A. Pacific Ocean
• B. Atlantic Ocean
• C. Arctic Ocean
• D. Indian Ocean

Explanation: The Indian Ocean is generally considered the warmest ocean because much of it lies in tropical latitudes and its northern part is enclosed by land. The Arctic Ocean is, by contrast, the coldest.

218. What is the name of the branch of the science that studies the ocean?

• A. Oceanography
• B. Algology
• C. Phology
• D. Orintology

Explanation: Oceanography is the scientific study of oceans, including their water, currents, marine life, geology, and atmosphere. Algology specifically concerns algae.

219. The lowest region of the earth's atmosphere comes between the earth and stratosphere. what is this region's name?

• A. Ionosphere
• B. Troposphere
• C. Stratosphere
• D. Mesosphere

Explanation: The troposphere is the lowest atmospheric layer, extending from Earth's surface up to the stratosphere. Most clouds and weather occur in this layer.

220. The study of the weather is called____________?

• A. Meteorology
• B. Weatherology
• C. Ecology
• D. Geology

Explanation: Meteorology studies the atmosphere and short-term weather phenomena such as temperature, wind, clouds, and rainfall. Geology studies Earth materials and structure, not daily weather.