Worksheet Solutions: The Atmosphere | Window on the Word Class 7: Solutions, Notes & Worksheets PDF Download

Q1: Multiple Choice Questions (MCQs)

(i) What holds the atmosphere to the surface of the Earth?
(a) Solar radiation
(b) Gravitational force
(c) Rotation of the Earth
(d) Air pressure
Ans: (b)
The atmosphere is held to the surface of the Earth by the planet's gravitational force.

(ii) Which gas makes up the largest portion of the Earth's atmosphere?
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Hydrogen
Ans: (c)
Nitrogen constitutes about 78% of the Earth's atmosphere.

(iii) The uppermost layer of the atmosphere, which merges with outer space, is called:
(a) Mesosphere
(b) Stratosphere
(c) Exosphere
(d) Thermosphere
Ans: (c)
The exosphere is the uppermost layer of the atmosphere.

(iv) What type of rainfall occurs when moist air rises due to heating of the land and forms towering cumulus clouds?
(a) Cyclonic rainfall
(b) Relief rainfall
(c) Convectional rainfall
(d) Planetary rainfall
Ans: (c)
Convectional rainfall is common near the equator and occurs when heated land causes moist air to rise and form clouds.

(v) The layer of the atmosphere that reflects radio waves and is important for radio communication is the:
(a) Mesosphere
(b) Troposphere
(c) Exosphere
(d) Ionosphere
Ans: (d)
The ionosphere, found in the thermosphere, reflects radio waves and aids in radio communication.

Q2: Fill in the Blanks

(i) Almost ____% of the atmosphere is composed of nitrogen.
Ans: 78%

(ii) The rise in average global temperature due to an increase in greenhouse gases is known as ____________.
Ans: Global warming

(iii) The troposphere contains all the gases essential for life and is where ______________ changes occur.
Ans: Weather

(iv) The atmospheric temperature decreases by about 1°C for every ______ meters of ascent in the troposphere.
Ans: 165

(v) Land and sea breezes are examples of ______________ winds.
Ans: Local

Q3: Match the Column

Match the items in Column A with the appropriate items in Column B.

Ans:

Q4: True or False

(i) The greenhouse effect is a natural phenomenon that has no relation to global warming.
Ans: False
The greenhouse effect is a natural process, but human activities have intensified it, leading to global warming.

(ii) Altitude affects atmospheric temperature, with higher altitudes being warmer than lower ones.
Ans: False
Higher altitudes are colder than lower altitudes due to thinner air.

(iii) Convectional rainfall occurs near the equator and results from rising warm air.
Ans: True
Convectional rainfall occurs due to the rising of warm, moist air near the equator.

(iv) Local winds like land and sea breezes blow in opposite directions during the day and night.
Ans: True
Land breezes blow from land to sea at night, while sea breezes blow from sea to land during the day.

(v) Absolute humidity measures the ratio of moisture to the air's capacity to hold moisture.
Ans: False
Absolute humidity measures the actual quantity of water vapor, not the ratio to air capacity. Relative humidity measures the ratio.