Consider the following statements regarding Carbon Dioxide (CO2) in the air: 1. It constitutes the largest component of the air around us. 2. It is produced by plants and animals during respiration. 3. Accumulation of CO2 in a closed room can cause suffocation. Which of the statements given above is/are correct?

The correct option is (c). Explanation The atmosphere is a mixture of various gases essential for life and Earth's physical processes. The composition of air is dominated by Nitrogen and Oxygen, with other gases present in trace amounts. Statement-wise Analysis: - Statement 1 is Incorrect. Carbon Dioxide (CO2) constitutes a very small fraction of the atmosphere, approximately 0.04%. The largest component of air is Nitrogen (approximately 78%), followed by Oxygen (approximately 21%) and Argon (approximately 0.93%). - Statement 2 is Correct. Carbon Dioxide is a metabolic byproduct produced by both plants and animals during respiration. In this process, organisms consume oxygen to break down organic compounds for energy, releasing CO2 into the atmosphere. - Statement 3 is Correct. In a closed or poorly ventilated room, processes like respiration or combustion can lead to the accumulation of CO2. Elevated levels of CO2 displace oxygen and can cause suffocation, dizziness, and respiratory distress due to oxygen deprivation and hypercapnia (toxicity caused by excessive CO2). Key Takeaway: Nitrogen is the most abundant gas in the atmosphere. Carbon Dioxide is a trace gas released during respiration; however, its accumulation in confined spaces is hazardous to health.

NCERT Class 6 Environment & Ecology — Chapter 2: Air around us

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Consider the following statements regarding Carbon Dioxide (CO2) in the air:

It constitutes the largest component of the air around us.
It is produced by plants and animals during respiration.
Accumulation of CO2 in a closed room can cause suffocation.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

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

Did you get this right?

Solution

The correct option is (c).

Explanation

The atmosphere is a mixture of various gases essential for life and Earth's physical processes. The composition of air is dominated by Nitrogen and Oxygen, with other gases present in trace amounts.

Statement-wise Analysis:

Statement 1 is Incorrect. Carbon Dioxide (CO₂) constitutes a very small fraction of the atmosphere, approximately 0.04%. The largest component of air is Nitrogen (approximately 78%), followed by Oxygen (approximately 21%) and Argon (approximately 0.93%).
Statement 2 is Correct. Carbon Dioxide is a metabolic byproduct produced by both plants and animals during respiration. In this process, organisms consume oxygen to break down organic compounds for energy, releasing CO₂ into the atmosphere.
Statement 3 is Correct. In a closed or poorly ventilated room, processes like respiration or combustion can lead to the accumulation of CO₂. Elevated levels of CO₂ displace oxygen and can cause suffocation, dizziness, and respiratory distress due to oxygen deprivation and hypercapnia (toxicity caused by excessive CO₂).

Key Takeaway:
Nitrogen is the most abundant gas in the atmosphere. Carbon Dioxide is a trace gas released during respiration; however, its accumulation in confined spaces is hazardous to health.

Your note

More from Chapter 2: Air around us

Consider the following statements regarding the atmosphere: 1. It is a thin layer of air that surrounds the earth. 2. It extends only up to 10 km above the surface of the earth. 3. The air becomes denser as we move higher in the atmosphere. Which of the statements given above is/are correct?

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With reference to the composition of air, consider the following statements: 1. Nitrogen and oxygen together make up approximately 99% of the air. 2. Carbon dioxide constitutes the majority of the remaining 1% of air. 3. The composition of air varies from place to place. Which of the statements given above is/are correct?

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Consider the following statements regarding water vapour in the air: 1. Air contains water vapour only during the rainy season. 2. When air comes in contact with a cool surface, water vapour condenses. 3. The presence of water vapour in air is essential for the water cycle in nature. Which of the statements given above is/are correct?

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With reference to the burning of fuel and its by-products, consider the following statements: 1. Burning can occur in the absence of oxygen if nitrogen is present. 2. Burning of fuel produces smoke which contains a few gases and fine dust particles. 3. Smoke produced by burning fuel is generally beneficial to respiratory health. Which of the statements given above is/are correct?

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Consider the following statements regarding the "dust particles" in the air: 1. Dust particles are always present in the air. 2. The presence of dust particles in air is constant irrespective of time and place. 3. Breathing through the mouth can allow harmful dust particles to enter the body. Which of the statements given above is/are correct?

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The correct option is (c).

Explanation

The atmosphere is a mixture of various gases essential for life and Earth's physical processes. The composition of air is dominated by Nitrogen and Oxygen, with other gases present in trace amounts.

Statement-wise Analysis:

Statement 1 is Incorrect. Carbon Dioxide (CO₂) constitutes a very small fraction of the atmosphere, approximately 0.04%. The largest component of air is Nitrogen (approximately 78%), followed by Oxygen (approximately 21%) and Argon (approximately 0.93%).
Statement 2 is Correct. Carbon Dioxide is a metabolic byproduct produced by both plants and animals during respiration. In this process, organisms consume oxygen to break down organic compounds for energy, releasing CO₂ into the atmosphere.
Statement 3 is Correct. In a closed or poorly ventilated room, processes like respiration or combustion can lead to the accumulation of CO₂. Elevated levels of CO₂ displace oxygen and can cause suffocation, dizziness, and respiratory distress due to oxygen deprivation and hypercapnia (toxicity caused by excessive CO₂).

Key Takeaway:
Nitrogen is the most abundant gas in the atmosphere. Carbon Dioxide is a trace gas released during respiration; however, its accumulation in confined spaces is hazardous to health.