With reference to the rusting of iron, consider the following statements: 1. Rust is chemically the same substance as iron. 2. The presence of both oxygen and water (or water vapour) is essential for rusting. 3. High humidity increases the rate of rusting. Which of the statements given above is/are correct?

The correct option is (c). Explanation Rusting is a chemical process involving the corrosion of iron. It is an oxidation reaction where iron reacts with atmospheric oxygen in the presence of moisture to form a reddish-brown substance known as rust. Statement-wise Analysis - Statement 1 is Incorrect. Rust and iron are not the same substance. Iron is a chemical element (Fe), whereas rust is a chemical compound called hydrated iron(III) oxide ($Fe_2O_3 \cdot xH_2O$). The formation of rust is a chemical change resulting in a new substance with properties different from the original metal. - Statement 2 is Correct. The process of rusting requires two essential conditions: the presence of oxygen (usually from the air) and the presence of water (or moisture). If either of these components is absent, rusting does not occur. - Statement 3 is Correct. Humidity refers to the amount of water vapour present in the air. High humidity implies a higher concentration of moisture, which facilitates the electrochemical process of corrosion. Therefore, the rate of rusting is significantly faster in humid environments compared to dry environments. Key Takeaway Rusting is the formation of hydrated iron oxide ($Fe_2O_3 \cdot xH_2O$) from iron. It is a chemical change that strictly requires both oxygen and water to proceed.

NCERT Class 7 Science — Chapter 2: Physical and chemical changes

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With reference to the rusting of iron, consider the following statements:

Rust is chemically the same substance as iron.
The presence of both oxygen and water (or water vapour) is essential for rusting.
High humidity increases the rate of rusting.

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

Rusting is a chemical process involving the corrosion of iron. It is an oxidation reaction where iron reacts with atmospheric oxygen in the presence of moisture to form a reddish-brown substance known as rust.

Statement-wise Analysis

Statement 1 is Incorrect. Rust and iron are not the same substance. Iron is a chemical element (Fe), whereas rust is a chemical compound called hydrated iron(III) oxide ($Fe_2O_3 \cdot xH_2O$). The formation of rust is a chemical change resulting in a new substance with properties different from the original metal.
Statement 2 is Correct. The process of rusting requires two essential conditions: the presence of oxygen (usually from the air) and the presence of water (or moisture). If either of these components is absent, rusting does not occur.
Statement 3 is Correct. Humidity refers to the amount of water vapour present in the air. High humidity implies a higher concentration of moisture, which facilitates the electrochemical process of corrosion. Therefore, the rate of rusting is significantly faster in humid environments compared to dry environments.

Key Takeaway

Rusting is the formation of hydrated iron oxide ($Fe_2O_3 \cdot xH_2O$) from iron. It is a chemical change that strictly requires both oxygen and water to proceed.

Your note

More from Chapter 2: Physical and chemical changes

With reference to the burning of a magnesium ribbon, consider the following statements: 1. It burns with a dull blue flame. 2. The ash formed is chemically different from the magnesium ribbon. 3. The reaction produces a new substance called magnesium oxide. Which of the statements given above is/are correct?

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When the ash obtained from burning magnesium is dissolved in water, the resulting solution is:

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With reference to the reaction between Copper Sulphate and Iron, consider the following statements: 1. The colour of the solution changes from blue to green. 2. The green colour is due to the formation of Copper Oxide. 3. A brown deposit forms on the iron object, which is Rust (Iron Oxide). Which of the statements given above is/are correct?

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Which of the following pairs is correctly matched regarding the reaction of Copper Sulphate with Iron?

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With reference to the "Lime Water Test", consider the following statements: 1. It is a standard test for Carbon Dioxide gas. 2. The milky appearance is due to the formation of Calcium Oxide. 3. The chemical name of lime water is Calcium Hydroxide. Which of the statements given above is/are correct?

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The correct option is (c).

Explanation

Statement-wise Analysis

Statement 1 is Incorrect. Rust and iron are not the same substance. Iron is a chemical element (Fe), whereas rust is a chemical compound called hydrated iron(III) oxide ($Fe_2O_3 \cdot xH_2O$). The formation of rust is a chemical change resulting in a new substance with properties different from the original metal.
Statement 2 is Correct. The process of rusting requires two essential conditions: the presence of oxygen (usually from the air) and the presence of water (or moisture). If either of these components is absent, rusting does not occur.
Statement 3 is Correct. Humidity refers to the amount of water vapour present in the air. High humidity implies a higher concentration of moisture, which facilitates the electrochemical process of corrosion. Therefore, the rate of rusting is significantly faster in humid environments compared to dry environments.

Key Takeaway

Rusting is the formation of hydrated iron oxide ($Fe_2O_3 \cdot xH_2O$) from iron. It is a chemical change that strictly requires both oxygen and water to proceed.