Consider the following statements regarding "smoke": 1. It is produced by burning fuel. 2. It is beneficial for health. 3. It consists entirely of water vapour. Which of the statements given above is/are correct?

The correct option is (a). Explanation Smoke is a visible suspension of carbon or other particles in the air, typically emitted from a burning substance. It is a form of air pollution classified as an aerosol, consisting of solid particles dispersed in a gas. - Statement 1 is Correct: Smoke is produced by the burning (combustion) of fuels such as wood, coal, petroleum, and other organic materials. The process releases a mixture of gases and fine particles into the atmosphere. - Statement 2 is Incorrect: Smoke is detrimental to health. It contains harmful substances, including particulate matter (PM), carbon monoxide, and carcinogenic compounds, which can cause respiratory ailments, eye irritation, and other serious health issues. - Statement 3 is Incorrect: Smoke does not consist entirely of water vapour. While water vapour is a byproduct of combustion, smoke is characterized by the presence of unburnt carbon particles (soot) and various gases (such as carbon dioxide and nitrogen oxides). A suspension consisting entirely of water droplets in the air is termed fog or mist, not smoke. Key Takeaway: Smoke is a harmful byproduct of combustion comprising a mixture of gases and solid particulate matter, distinct from pure water vapour.

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

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Consider the following statements regarding "smoke":

It is produced by burning fuel.
It is beneficial for health.
It consists entirely of water vapour.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

The correct option is (a).

Explanation

Smoke is a visible suspension of carbon or other particles in the air, typically emitted from a burning substance. It is a form of air pollution classified as an aerosol, consisting of solid particles dispersed in a gas.

Statement 1 is Correct: Smoke is produced by the burning (combustion) of fuels such as wood, coal, petroleum, and other organic materials. The process releases a mixture of gases and fine particles into the atmosphere.
Statement 2 is Incorrect: Smoke is detrimental to health. It contains harmful substances, including particulate matter (PM), carbon monoxide, and carcinogenic compounds, which can cause respiratory ailments, eye irritation, and other serious health issues.
Statement 3 is Incorrect: Smoke does not consist entirely of water vapour. While water vapour is a byproduct of combustion, smoke is characterized by the presence of unburnt carbon particles (soot) and various gases (such as carbon dioxide and nitrogen oxides). A suspension consisting entirely of water droplets in the air is termed fog or mist, not smoke.

Key Takeaway: Smoke is a harmful byproduct of combustion comprising a mixture of gases and solid particulate matter, distinct from pure water vapour.

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?

medium

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 (a).

Explanation

Statement 1 is Correct: Smoke is produced by the burning (combustion) of fuels such as wood, coal, petroleum, and other organic materials. The process releases a mixture of gases and fine particles into the atmosphere.
Statement 2 is Incorrect: Smoke is detrimental to health. It contains harmful substances, including particulate matter (PM), carbon monoxide, and carcinogenic compounds, which can cause respiratory ailments, eye irritation, and other serious health issues.
Statement 3 is Incorrect: Smoke does not consist entirely of water vapour. While water vapour is a byproduct of combustion, smoke is characterized by the presence of unburnt carbon particles (soot) and various gases (such as carbon dioxide and nitrogen oxides). A suspension consisting entirely of water droplets in the air is termed fog or mist, not smoke.

Key Takeaway: Smoke is a harmful byproduct of combustion comprising a mixture of gases and solid particulate matter, distinct from pure water vapour.