Consider the following statements regarding the volume of gases in the atmosphere: 1. The volume of carbon dioxide has remained constant in the past few decades. 2. The volume of other gases (besides CO2) is considered constant. 3. The rise in CO2 is mainly due to the burning of fossil fuels. Which of the statements given above is/are correct?

Correct Option The correct option is 2 and 3 only. Explanation The atmosphere consists of a mixture of gases classified into permanent gases and variable gases. Permanent gases maintain a fixed proportion in the total volume of the lower atmosphere, while variable gases change in concentration due to natural and anthropogenic processes. Statement-wise Analysis - Statement 1 is Incorrect: Carbon dioxide (CO2) is a variable gas. Its volume has not remained constant; it has been rising steadily over the past few decades. This increase is a significant concern regarding global warming and climate change. - Statement 2 is Correct: The major gases such as Nitrogen (78.08%), Oxygen (20.95%), and Argon (0.93%) are considered permanent gases. Their relative percentages in the atmosphere remain virtually constant over recent history, unlike variable gases such as CO2, water vapour, and ozone. - Statement 3 is Correct: The rapid rise in atmospheric carbon dioxide concentration is primarily attributed to human activities. The burning of fossil fuels (coal, oil, and natural gas) releases large amounts of CO2, altering the natural balance of the atmosphere. Key Takeaway Key Takeaway: Nitrogen and Oxygen are permanent gases with constant proportions, whereas Carbon Dioxide is a variable gas whose concentration is increasing mainly due to fossil fuel combustion.

NCERT Class 11 Geography — Chapter 1: Composition and Structure of Atmosphere

mcqeasy

Consider the following statements regarding the volume of gases in the atmosphere:

The volume of carbon dioxide has remained constant in the past few decades.
The volume of other gases (besides CO2) is considered constant.
The rise in CO2 is mainly due to the burning of fossil fuels.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 and 2 only
B2 and 3 only
C2 only
D1, 2 and 3

Did you get this right?

Solution

Correct Option

The correct option is 2 and 3 only.

Explanation

The atmosphere consists of a mixture of gases classified into permanent gases and variable gases. Permanent gases maintain a fixed proportion in the total volume of the lower atmosphere, while variable gases change in concentration due to natural and anthropogenic processes.

Statement-wise Analysis

Statement 1 is Incorrect: Carbon dioxide (CO₂) is a variable gas. Its volume has not remained constant; it has been rising steadily over the past few decades. This increase is a significant concern regarding global warming and climate change.
Statement 2 is Correct: The major gases such as Nitrogen (78.08%), Oxygen (20.95%), and Argon (0.93%) are considered permanent gases. Their relative percentages in the atmosphere remain virtually constant over recent history, unlike variable gases such as CO₂, water vapour, and ozone.
Statement 3 is Correct: The rapid rise in atmospheric carbon dioxide concentration is primarily attributed to human activities. The burning of fossil fuels (coal, oil, and natural gas) releases large amounts of CO₂, altering the natural balance of the atmosphere.

Key Takeaway

Key Takeaway: Nitrogen and Oxygen are permanent gases with constant proportions, whereas Carbon Dioxide is a variable gas whose concentration is increasing mainly due to fossil fuel combustion.

Your note

More from Chapter 1: Composition and Structure of Atmosphere

Consider the following statements regarding the composition of the atmosphere: 1. The proportion of gases remains constant up to the highest layers of the atmosphere. 2. Nitrogen is the most abundant gas in the atmosphere. 3. Nitrogen and Oxygen make up the bulk of the atmosphere. Which of the statements given above is/are correct?

easy

Which of the following is the main reason for the rising volume of carbon dioxide in the atmosphere?

easy

Consider the following statements regarding water vapour in the atmosphere: 1. It is a variable gas that increases with altitude. 2. It accounts for less than one % of the air by volume in the dry and cold polar regions. 3. It absorbs parts of the insolation from the sun and preserves the earth’s radiated heat. Which of the statements given above is/are correct?

medium

With reference to the composition of the atmosphere, consider the following statements: 1. Oxygen is found in substantial quantities at heights above 120 km from the earth's surface. 2. Carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation. 3. Carbon dioxide and water vapour are found in uniform concentration up to the exosphere. Which of the statements given above is/are correct?

medium

Which one of the following is the most likely reason for the higher concentration of dust particles in subtropical and temperate regions compared to equatorial regions?

easy

Keep practising Chapter 1: Composition and Structure of Atmosphere

Work through every question from this NCERT chapter.

Browse all NCERT Class 11 Geography chapters

Correct Option

The correct option is 2 and 3 only.

Explanation

Statement-wise Analysis

Statement 1 is Incorrect: Carbon dioxide (CO₂) is a variable gas. Its volume has not remained constant; it has been rising steadily over the past few decades. This increase is a significant concern regarding global warming and climate change.
Statement 2 is Correct: The major gases such as Nitrogen (78.08%), Oxygen (20.95%), and Argon (0.93%) are considered permanent gases. Their relative percentages in the atmosphere remain virtually constant over recent history, unlike variable gases such as CO₂, water vapour, and ozone.
Statement 3 is Correct: The rapid rise in atmospheric carbon dioxide concentration is primarily attributed to human activities. The burning of fossil fuels (coal, oil, and natural gas) releases large amounts of CO₂, altering the natural balance of the atmosphere.

Key Takeaway

Key Takeaway: Nitrogen and Oxygen are permanent gases with constant proportions, whereas Carbon Dioxide is a variable gas whose concentration is increasing mainly due to fossil fuel combustion.