All Free Everyday Science MCQs with Answers

861. 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.

862. 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.

863. 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.

864. 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.

865. 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.

866. Second layer of Earth's atmosphere is__________?

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

Explanation: From the ground upward, the atmospheric layers are troposphere, stratosphere, mesosphere and thermosphere. Therefore, the stratosphere is the second layer.

867. Average salinity or ratio of salt as per kilogram of water of ocean is__________?

• A. 35 grams
• B. 55 grams
• C. 32 grams
• D. 42 grams

Explanation: Average ocean salinity is about 35 grams of dissolved salts per kilogram of seawater, often written as 35 parts per thousand. Local salinity varies because of evaporation, rainfall and freshwater input.

868. Sum of all ecosystems is classified as___________?

• A. Aero sphere
• B. Ionosphere
• C. Biosphere
• D. Ozonosphere

Explanation: The biosphere is the global zone of life and includes all ecosystems together. The ionosphere and ozonosphere are specialized atmospheric regions, not the sum of ecosystems.

869. Ice mass that covers more than fifty-thousand square kilometers of land area is classified as____________?

• A. ice sheet
• B. ice field
• C. glacier erosions
• D. ice cap

Explanation: An ice sheet is a continental-scale ice mass covering more than 50,000 square kilometres. Smaller regional masses are called ice caps or ice fields.

870. Evaporation from ice and snow is known as___________?

• A. evaporation
• B. sublimation
• C. hydrogenation
• D. insolation

Explanation: Sublimation is the direct change of ice or snow from solid to water vapour without first becoming liquid. Evaporation normally refers to liquid water changing into vapour.