Free Environment and Atmosphere MCQs with Answers

261. In middle latitudes, which cloud will have the lowest base ________________________ ?

• A. Cirrostratus
• B. Stratocumulus
• C. Altocumulus
• D. Cirrus

Explanation: Stratocumulus is a low-level cloud, so its base is lower than those of middle-level altocumulus and high-level cirrus or cirrostratus. The cloud name and altitude category provide the useful clue.

262. The blueness of the sky is mainly due to _____________?

• A. The scattering of sunlight by air molecules
• B. The presence of water vapor
• C. Absorption of blue light by the air
• D. Emission of blue light by the atmosphere

Explanation: Air molecules scatter short-wavelength blue light more strongly than longer-wavelength red light, so scattered blue light reaches the observer from all directions. Water vapour is not the main cause of the sky's blue colour.

263. The atmosphere near the earth's surface is "heated from below." Which of the following does not significantly contribute to this heating _____________________?

• A. Conduction of heat upward from a hot surface
• B. Convection from a hot surface
• C. Absorption of infrared energy that has been radiated from the surface
• D. Heat energy from the earth's interior

Explanation: The surface warms the lower atmosphere through conduction, convection and absorption of outgoing infrared radiation. Heat from Earth's interior is negligible compared with solar energy at the surface.

264. The gradual physiological adjustment to slowly changing new environmental conditions is known as _____________________?

• A. Selection
• B. Introduction
• C. Acclimatization
• D. Quarantine

Explanation: Acclimatization is the gradual physiological adjustment of an individual to a changed environment, such as reduced oxygen at high altitude. Selection changes populations across generations, not an individual's adjustment.

265. Salinization is ___________?

• A. Accumulation of salts in water
• B. Accumulation of salts in soil
• C. Accumulation of salts in body
• D. Accumulation of salts in animals

Explanation: Salinization is the build-up of soluble salts in soil, often caused by irrigation and evaporation in dry regions. Excess soil salt makes it difficult for plants to absorb water.

266. Acid deposition causes ______________________?

• A. the greenhouse effect to lessen
• B. lakes and forests to die
• C. acid indigestion in humans
• D. all the above are correct

Explanation: Acid deposition lowers the pH of lakes and soils and can damage or kill aquatic life and forests. It does not cause ordinary human acid indigestion, so the combined option is not correct.

267. Water vapor is ______________?

• A. A gas
• B. A cloud droplet
• C. A rain drop
• D. A snowflake

Explanation: Water vapour is water in its gaseous state, produced when liquid water evaporates or ice sublimates. Clouds, raindrops and snowflakes are condensed or frozen forms of water.

268. At what time of day is the relative humidity normally at a minimum ________________ ?

• A. When the air temperature is highest
• B. Just before sunrise
• C. About midnight
• D. When the air temperature is lowest

Explanation: Relative humidity usually falls when air temperature rises, because warmer air can hold more water vapour without becoming saturated. It is therefore normally lowest near the day's maximum temperature.

269. The atmospheric greenhouse effect is produced mainly by the __________________?

• A. Absorption and re-emission of visible light by the atmosphere
• B. Absorption and re-emission of ultraviolet radiation by the atmosphere
• C. Absorption and re-emission of infrared radiation by the atmosphere
• D. Absorption and re-emission of visible light by clouds
• E. Absorption and re-emission of visible light by the ground

Explanation: Earth's surface absorbs sunlight and emits infrared radiation, which greenhouse gases absorb and re-emit in the atmosphere. This infrared trapping warms the lower atmosphere and surface.

270. what is the height of The atmosphere layer mesosphere?

• A. 85 km
• B. 50 km
• C. 40 km
• D. 10 km

Explanation: The mesosphere extends from about 50 km to approximately 85 km above Earth's surface, so 85 km marks its usual upper boundary. It lies above the stratosphere and below the thermosphere.