Which of the following is a correct statement about "Carbon Dioxide"? 1. It is consumed during the process of burning. 2. It is produced during respiration. 3. It is a component of the air we exhale. Select the correct answer using the code given below:

Correct Option The correct option is (c). Explanation Carbon Dioxide (CO2) is a naturally occurring gas in the Earth's atmosphere. It plays a critical role in the carbon cycle, involving processes such as photosynthesis, respiration, and combustion. Understanding the reactants and products of these chemical reactions is essential to identifying the correct properties of the gas. Statement-wise Analysis - Statement 1 is Incorrect: Combustion (burning) is a chemical process where a substance reacts rapidly with oxygen and gives off heat. During the burning of carbon-based fuels (such as wood, coal, or petrol), oxygen is consumed from the atmosphere, and Carbon Dioxide is produced (released) as a byproduct, not consumed. - Statement 2 is Correct: Respiration is the metabolic process by which living organisms produce energy. In aerobic respiration, glucose reacts with oxygen to release energy, producing water and Carbon Dioxide as waste products. Therefore, CO2 is generated during respiration. - Statement 3 is Correct: Since Carbon Dioxide is a byproduct of cellular respiration, it is transported by the blood to the lungs to be expelled from the body. Consequently, the air we exhale contains a significantly higher concentration of Carbon Dioxide (approximately 4-5%) compared to the air we inhale (approximately 0.04%). Key Takeaway Combustion and Respiration both consume Oxygen and release Carbon Dioxide. Conversely, Photosynthesis consumes Carbon Dioxide and releases Oxygen.

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

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Which of the following is a correct statement about "Carbon Dioxide"?

It is consumed during the process of burning.
It is produced during respiration.
It is a component of the air we exhale.

Select the correct answer using the code given below:

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

Correct Option

The correct option is (c).

Explanation

Carbon Dioxide (CO₂) is a naturally occurring gas in the Earth's atmosphere. It plays a critical role in the carbon cycle, involving processes such as photosynthesis, respiration, and combustion. Understanding the reactants and products of these chemical reactions is essential to identifying the correct properties of the gas.

Statement-wise Analysis

Statement 1 is Incorrect: Combustion (burning) is a chemical process where a substance reacts rapidly with oxygen and gives off heat. During the burning of carbon-based fuels (such as wood, coal, or petrol), oxygen is consumed from the atmosphere, and Carbon Dioxide is produced (released) as a byproduct, not consumed.
Statement 2 is Correct: Respiration is the metabolic process by which living organisms produce energy. In aerobic respiration, glucose reacts with oxygen to release energy, producing water and Carbon Dioxide as waste products. Therefore, CO₂ is generated during respiration.
Statement 3 is Correct: Since Carbon Dioxide is a byproduct of cellular respiration, it is transported by the blood to the lungs to be expelled from the body. Consequently, the air we exhale contains a significantly higher concentration of Carbon Dioxide (approximately 4-5%) compared to the air we inhale (approximately 0.04%).

Key Takeaway

Combustion and Respiration both consume Oxygen and release Carbon Dioxide. Conversely, Photosynthesis consumes Carbon Dioxide and releases Oxygen.

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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Correct Option

The correct option is (c).

Explanation

Statement-wise Analysis

Statement 1 is Incorrect: Combustion (burning) is a chemical process where a substance reacts rapidly with oxygen and gives off heat. During the burning of carbon-based fuels (such as wood, coal, or petrol), oxygen is consumed from the atmosphere, and Carbon Dioxide is produced (released) as a byproduct, not consumed.
Statement 2 is Correct: Respiration is the metabolic process by which living organisms produce energy. In aerobic respiration, glucose reacts with oxygen to release energy, producing water and Carbon Dioxide as waste products. Therefore, CO₂ is generated during respiration.
Statement 3 is Correct: Since Carbon Dioxide is a byproduct of cellular respiration, it is transported by the blood to the lungs to be expelled from the body. Consequently, the air we exhale contains a significantly higher concentration of Carbon Dioxide (approximately 4-5%) compared to the air we inhale (approximately 0.04%).

Key Takeaway

Combustion and Respiration both consume Oxygen and release Carbon Dioxide. Conversely, Photosynthesis consumes Carbon Dioxide and releases Oxygen.