Worksheet Solutions: The Atmosphere | Footprints Class 7: Book Solutions, Notes & Worksheets PDF Download

Multiple Choice Questions (MCQs)

Q1: What is the primary function of the ozone layer within the stratosphere?
(a) To create weather patterns
(b) To absorb and scatter ultraviolet radiation from the Sun
(c) To produce oxygen for respiration
(d) To regulate Earth’s temperature
Ans: (b) To absorb and scatter ultraviolet radiation from the Sun
The ozone layer is crucial because it absorbs and scatters the majority of the sun's harmful ultraviolet radiation, preventing it from reaching the surface of the Earth and thereby protecting living organisms from its damaging effects.

Q2: Which of the following gases is the most abundant in Earth's atmosphere?
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Argon
Ans: (c) Nitrogen
Nitrogen makes up about 78% of the Earth's atmosphere, making it the most abundant gas. It is inert under most conditions and plays a critical role in the biosphere, particularly in the nitrogen cycle.

Q3: In which atmospheric layer do most weather phenomena occur?
(a) Exosphere
(b) Thermosphere
(c) Stratosphere
(d) Troposphere
Ans: (d) Troposphere
The troposphere is the lowest layer of Earth's atmosphere and is where almost all weather conditions take place, including clouds, rain, and snow, due to its dense composition of air and moisture.

Q4: What is the significance of carbon dioxide in the atmosphere?
(a) It is essential for respiration in animals.
(b) It is the primary source of nitrogen for plants.
(c) It plays a crucial role in photosynthesis and the greenhouse effect.
(d) It acts as a primary buffer in Earth's oceans.
Ans: (c) It plays a crucial role in photosynthesis and the greenhouse effect.
Carbon dioxide is a minor but very important component of the atmosphere, vital for photosynthesis in plants and contributing to the greenhouse effect, which helps to regulate Earth's temperature.

Q5: What causes winds to move from one area to another?
(a) Movement of tectonic plates
(b) Uneven heating of Earth’s surface
(c) The rotation of the Moon around Earth
(d) Changes in the Earth's magnetic field
Ans: (b) Uneven heating of Earth’s surface
Winds are primarily caused by the uneven heating of the Earth's surface, leading to areas of different pressures. Air moves from high-pressure areas to low-pressure areas, forming winds.

Fill in the Blanks

Q1: The most abundant gas in the Earth's atmosphere, making up about 78%, is ______.
Ans: Nitrogen
Nitrogen is the most plentiful gas in the atmosphere, essential for life but inert in its molecular form.

Q2: The layer of the atmosphere where the International Space Station orbits is called the ______.
Ans: Thermosphere
The thermosphere is the layer above the mesosphere, characterized by high temperatures and where many satellites, including the ISS, orbit Earth.

Q3: The process by which plants convert carbon dioxide into oxygen and glucose is known as ______.
Ans: Photosynthesis
Photosynthesis is a critical biological process carried out by plants, involving the conversion of light energy into chemical energy, which produces oxygen as a byproduct.

Q4: ______ refers to the short-term atmospheric conditions such as temperature and precipitation in a given area.
Ans: Weather
Weather encompasses the day-to-day meteorological conditions in a specific place and can change rapidly.

Q5: The ______ is the zone on Earth that receives the most direct sunlight and is characterized by consistently high temperatures.
Ans: Torrid Zone
The Torrid Zone, also known as the tropics, spans the area between the Tropic of Cancer and the Tropic of Capricorn, receiving the most direct sunlight year-round.

True/False

Q1: Argon makes up approximately 21% of the Earth's atmosphere.
Ans: False
Oxygen, not argon, makes up approximately 21% of the atmosphere. Argon is much less abundant, making up about 0.93%.

Q2: The exosphere is the lowest layer of the Earth's atmosphere.
Ans: False
The troposphere is the lowest layer of the atmosphere. The exosphere is the outermost layer, gradually transitioning into space.

Q3: Humidity is a measure of the amount of carbon dioxide in the air.
Ans: False
Humidity measures the amount of water vapor in the air, not carbon dioxide.

Q4: Atmospheric pressure increases with altitude.
Ans: False
Atmospheric pressure decreases with altitude because there is less air above to exert pressure as altitude increases.

Q5: The ozone layer is located in the mesosphere.
Ans: False
The ozone layer is actually located in the stratosphere, not the mesosphere. It plays a crucial role in absorbing ultraviolet radiation.

Match the Column

Ans:

• A - 4: The troposphere is the primary layer where most weather phenomena occur.
• B - 3: Carbon dioxide is essential for photosynthesis, the process by which plants produce food.
• C - 2: Winds are caused by the uneven heating of Earth's surface.
• D - 1: Nitrogen is the most abundant gas in the atmosphere.
• E - 5: Humidity refers to the amount of water vapor present in the air.