Free Environment and Atmosphere MCQs with Answers

61. Stratosphere is present at an altitude between _________.

• A. 15 km and 35 km
• B. 17 km and 35 km
• C. 18 km and 35 km
• D. 19 km and 35 km

Explanation: Many basic texts place the stratosphere approximately between 15 and 35 km in this simplified classification, although broader scientific definitions extend it from roughly 12 to 50 km. The question follows the narrower textbook range represented by option a.

62. _________ extends from the top of the troposphere to the bottom of the mesosphere.

• A. Thermosphere
• B. Ionosphere
• C. Stratosphere
• D. None of the above

Explanation: The stratosphere begins at the top of the troposphere and ends at the stratopause, below the mesosphere. The thermosphere lies much higher, while the ionosphere overlaps several atmospheric layers.

63. ____________ contains 75-80 % of the mass of the atmosphere.

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

Explanation: The troposphere contains most atmospheric mass because gravity concentrates air near Earth’s surface. It also holds nearly all atmospheric water vapour and clouds.

64. Troposphere extends from planetary surface to bottom of __________?

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

Explanation: The troposphere extends upward from Earth’s surface to the tropopause, which is the bottom boundary of the stratosphere. Thus, the next atmospheric layer is the stratosphere.

65. __________ is the lowest layer of the atmosphere.

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

Explanation: The troposphere is the lowest atmospheric layer and is where humans live and most weather occurs. Above it lies the stratosphere.

66. Which is the New & Most Important Culprit damaging the ozone Layer?

• A. Carbon Dioxide
• B. Chlorofluoro Carbons
• C. Nitrous Oxide
• D. Carbon Monoxide

Explanation: Although CFCs caused the historic ozone hole, nitrous oxide is now regarded as the leading human-emitted ozone-depleting substance because it continues to reach the stratosphere in large amounts. It produces reactive nitrogen compounds that destroy ozone.

67. The color of a sedimentary rock is often mostly determined by___________?

• A. Zinc
• B. Iron
• C. Calcium
• D. None of these

Explanation: Iron compounds, especially iron oxides, commonly give sedimentary rocks red, brown, yellow, or orange shades. Zinc and calcium may occur in rocks but do not usually dominate their overall colour.

68. Carpology is a discipline devoted to the study of what?

• A. Corbons
• B. Cubes
• C. Seeds and fruits
• D. Infertile soils

Explanation: Carpology is the branch of botany concerned with fruits and seeds, including their structure and development. The term comes from Greek words associated with fruit.

69. Which insect can survive without a head for one or more weeks?

• A. Ladybird
• B. Bee
• C. Cockroach
• D. Termite

Explanation: Cockroaches can survive for weeks after losing their heads because they breathe through body openings and have a simple circulatory system. They eventually die mainly from starvation or dehydration.

70. What time of day do most owls hunt?

• A. Morning
• B. Afternoon
• C. Evening
• D. Night

Explanation: Most owl species are nocturnal, meaning they are most active and hunt at night. Some species hunt during the day or at twilight, but night is the standard answer.