Free Environment and Atmosphere MCQs with Answers

271. 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.

272. 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.

273. 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.

274. 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.

275. 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.

276. What is the name of the central part of the earth?

• A. Mantle
• B. Core
• C. Crust
• D. None of the above

Explanation: The core is Earth's central layer, surrounding the inner core with the liquid outer core. The mantle lies outside the core, while the crust is the thin outer surface.

277. The rocks formed out of layers of sediment bonded together are known as _______________?

• A. Metamorphic rocks
• B. Sedimentary rocks
• C. Igneous rocks
• D. All of the above

Explanation: Sedimentary rocks form when layers of sediment are deposited, compacted and cemented together. Igneous rocks solidify from molten material, while metamorphic rocks are altered by heat and pressure.

278. Which one is the world's largest mangrove forest(s)?

• A. Changa Manga Forest
• B. Amazon Forest
• C. Sundarbans Forest
• D. None of the above

Explanation: The Sundarbans is the world's largest continuous mangrove forest, spread across the delta of the Ganges, Brahmaputra and Meghna rivers. Changa Manga and the Amazon are not mangrove forests of this type.

279. The point that lies directly above the source of an earthquake is known as _______________ ?

• A. Earthquake Center
• B. Epicenter
• C. Gravitational Center
• D. Geological Center

Explanation: The epicentre is the point on Earth's surface directly above the earthquake's focus, where the rupture begins underground. The focus is the actual source within Earth.

280. Which pollutant from motor car exhaust causes mental disease _____?

• A. Carbon dioxide
• B. Lead
• C. Sulpher Dioxide
• D. Mercury

Explanation: Lead particles and compounds from vehicle exhaust, especially from formerly leaded petrol, can damage the nervous system and impair mental development. Carbon dioxide is a greenhouse gas, but it is not the pollutant associated with this specific neurological effect.