With reference to stresses in earth materials, consider the following statements: 1. Molecular stresses are unaffected by temperature changes. 2. Shear stresses are separating forces acting along the faces of earth materials. 3. Gravitational stress is the only stress that breaks rocks. Which of the statements given above is/are correct?

The correct option is 2 only Explanation Geomorphic processes are driven by forces that create stress within earth materials. These stresses lead to deformation, fracturing, and movement of rock masses. Understanding the nature of these stresses is essential to analyzing weathering and mass movements. Statement-wise Analysis: - Statement 1 is Incorrect: Shear stresses are forces that act tangentially or parallel to the surfaces of earth materials. In the context of geomorphic processes, they are described as separating forces because they break the continuity of the material by causing slippage or fracture along specific planes. - Statement 2 is Correct: Molecular stresses are directly influenced by factors such as temperature changes, crystallization, and melting. For instance, thermal expansion and contraction due to temperature fluctuations generate significant molecular stress within rocks, leading to disintegration. - Statement 3 is Incorrect: While gravitational stress (force of gravity per unit area) is a fundamental force affecting earth materials, it is not the only stress that breaks rocks. Rocks are also broken by molecular stresses (thermal expansion), chemical stresses (crystal growth), and tectonic stresses. Key Takeaway: Shear stress acts along the faces of materials to separate them, while molecular stress is induced by internal changes such as temperature fluctuations and crystallization.

NCERT Class 11 Geography — Chapter 4: Geomorphic Processes

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With reference to stresses in earth materials, consider the following statements:

Molecular stresses are unaffected by temperature changes.
Shear stresses are separating forces acting along the faces of earth materials.
Gravitational stress is the only stress that breaks rocks.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A2 only
B1, 2 and 3
C1 only
D1 and 3 only

Did you get this right?

Solution

The correct option is

2 only

Explanation

Geomorphic processes are driven by forces that create stress within earth materials. These stresses lead to deformation, fracturing, and movement of rock masses. Understanding the nature of these stresses is essential to analyzing weathering and mass movements.

Statement-wise Analysis:

Statement 1 is Incorrect: Shear stresses are forces that act tangentially or parallel to the surfaces of earth materials. In the context of geomorphic processes, they are described as separating forces because they break the continuity of the material by causing slippage or fracture along specific planes.
Statement 2 is Correct: Molecular stresses are directly influenced by factors such as temperature changes, crystallization, and melting. For instance, thermal expansion and contraction due to temperature fluctuations generate significant molecular stress within rocks, leading to disintegration.
Statement 3 is Incorrect: While gravitational stress (force of gravity per unit area) is a fundamental force affecting earth materials, it is not the only stress that breaks rocks. Rocks are also broken by molecular stresses (thermal expansion), chemical stresses (crystal growth), and tectonic stresses.

Key Takeaway:
Shear stress acts along the faces of materials to separate them, while molecular stress is induced by internal changes such as temperature fluctuations and crystallization.

Your note

More from Chapter 4: Geomorphic Processes

Consider the following statements comparing landslides in the Himalayas and the Western Ghats: 1. The Himalayas are tectonically active and made of sedimentary rocks, leading to frequent landslides. 2. The Western Ghats are tectonically active and made of soft sedimentary rocks. 3. Landslides occur in the Western Ghats despite their stability. Which of the statements given above is/are correct?

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Consider the following statements regarding the relationship between weathering and erosion: 1. Weathering is a pre-condition for erosion. 2. Weathering aids erosion. 3. Erosion has no significant impact on the earth's surface. Which of the statements given above is/are correct?

medium

Denudational processes such as erosion and transportation are primarily governed by:

easy

The development of Karst topography requires bedrock that is:

easy

Consider the following statements regarding mass movements: 1. They transfer the mass of rock debris down the slopes under the direct influence of gravity. 2. Running water and wind are the primary geomorphic agents that participate in the process of mass movements. 3. They are very active over weathered slopes rather than over unweathered materials. Which of the statements given above is/are correct?

medium

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The correct option is

2 only

Explanation

Statement-wise Analysis:

Statement 1 is Incorrect: Shear stresses are forces that act tangentially or parallel to the surfaces of earth materials. In the context of geomorphic processes, they are described as separating forces because they break the continuity of the material by causing slippage or fracture along specific planes.
Statement 2 is Correct: Molecular stresses are directly influenced by factors such as temperature changes, crystallization, and melting. For instance, thermal expansion and contraction due to temperature fluctuations generate significant molecular stress within rocks, leading to disintegration.
Statement 3 is Incorrect: While gravitational stress (force of gravity per unit area) is a fundamental force affecting earth materials, it is not the only stress that breaks rocks. Rocks are also broken by molecular stresses (thermal expansion), chemical stresses (crystal growth), and tectonic stresses.

Key Takeaway:
Shear stress acts along the faces of materials to separate them, while molecular stress is induced by internal changes such as temperature fluctuations and crystallization.