NCERT Class 11 Science — Chapter 4: Breathing and Exchange of Gases

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Which capacity is defined as the total volume of air that remains in the lungs after a normal expiration?

Official previous-year question

Verified 1 Aug 2026.

Options

ATotal Lung Capacity
BVital Capacity
CFunctional Residual Capacity
DExpiratory Capacity

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Solution

The correct option is Functional Residual Capacity.

Explanation

Respiratory capacities are calculated by summing specific respiratory volumes to describe the functional status of the lungs. These measurements are essential for assessing pulmonary function.

Analysis of Options:

Functional Residual Capacity (FRC): This is defined as the volume of air that remains in the lungs after a normal expiration. It is the sum of the Expiratory Reserve Volume (ERV) and the Residual Volume (RV). Mathematically, FRC = ERV + RV.
Vital Capacity (VC): This is the maximum volume of air a person can breathe in after a forced expiration. It includes the Expiratory Reserve Volume, Tidal Volume, and Inspiratory Reserve Volume (VC = ERV + TV + IRV).
Expiratory Capacity (EC): This is the total volume of air a person can expire after a normal inspiration. It consists of the Tidal Volume and the Expiratory Reserve Volume (EC = TV + ERV).
Total Lung Capacity (TLC): This refers to the total volume of air accommodated in the lungs at the end of a forced inspiration. It includes the Residual Volume, Expiratory Reserve Volume, Tidal Volume, and Inspiratory Reserve Volume (TLC = RV + ERV + TV + IRV).

Key Takeaway: Functional Residual Capacity (FRC) specifically refers to the air remaining in the lungs during the pause between breaths in a normal respiratory cycle.

Your note

More from Chapter 4: Breathing and Exchange of Gases

Consider the following statements about the larynx and epiglottis in humans: 1. Larynx is a cartilaginous box associated with sound production. 2. Epiglottis facilitates the entry of food into the larynx. 3. Epiglottis is a fibrous flap devoid of elasticity. Which of the statements given above is/are correct?

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Consider the following about diffusion of gases in the lungs: 1. It is driven mainly by partial pressure gradients. 2. Solubility of gases has no effect on the rate. 3. Membrane thickness influences the rate of diffusion. Which of the statements given above is/are correct?

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Which of the following pathways accounts for the majority of carbon dioxide transport in blood?

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Which enzyme predominantly present in RBCs catalyses the reversible formation of bicarbonate from carbon dioxide and water?

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With reference to gas exchange mechanisms among animals, consider the following statements: 1. Insects rely on gills for respiration. 2. Most aquatic arthropods depend on vascularised bags for respiration. 3. Most aquatic arthropods depend on gills for respiration. Which of the statements given above are correct?

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The correct option is Functional Residual Capacity.

Explanation

Respiratory capacities are calculated by summing specific respiratory volumes to describe the functional status of the lungs. These measurements are essential for assessing pulmonary function.

Analysis of Options:

Functional Residual Capacity (FRC): This is defined as the volume of air that remains in the lungs after a normal expiration. It is the sum of the Expiratory Reserve Volume (ERV) and the Residual Volume (RV). Mathematically, FRC = ERV + RV.
Vital Capacity (VC): This is the maximum volume of air a person can breathe in after a forced expiration. It includes the Expiratory Reserve Volume, Tidal Volume, and Inspiratory Reserve Volume (VC = ERV + TV + IRV).
Expiratory Capacity (EC): This is the total volume of air a person can expire after a normal inspiration. It consists of the Tidal Volume and the Expiratory Reserve Volume (EC = TV + ERV).
Total Lung Capacity (TLC): This refers to the total volume of air accommodated in the lungs at the end of a forced inspiration. It includes the Residual Volume, Expiratory Reserve Volume, Tidal Volume, and Inspiratory Reserve Volume (TLC = RV + ERV + TV + IRV).

Key Takeaway: Functional Residual Capacity (FRC) specifically refers to the air remaining in the lungs during the pause between breaths in a normal respiratory cycle.