Volume of air that will remain in the lungs after normal expiration is equal to

Options

A. TV + ERV
B. TV + IRV
C. VC + ERV
D. ERV + RV

Answer

To solve the question regarding the volume of air that remains in the lungs after normal expiration, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept**: The volume of air that remains in the lungs after normal expiration is referred to as the Functional Residual Capacity (FRC).

2. **Identify the Components of FRC**: The Functional Residual Capacity is made up of two components:
- **Expiratory Reserve Volume (ERV)**: This is the additional amount of air that can be forcibly exhaled after the expiration of a normal tidal volume.
- **Residual Volume (RV)**: This is the volume of air remaining in the lungs after a forced expiration, which cannot be expelled.

3. **Formula for FRC**: The formula for Functional Residual Capacity can be expressed as:
\[ FRC = ERV + RV \]

4. **Conclusion**: Therefore, the volume of air that remains in the lungs after normal expiration is equal to the sum of the Expiratory Reserve Volume and the Residual Volume.

5. **Final Answer**: The correct answer is that the volume of air that will remain in the lungs after normal expiration is equal to **ERV + RV**.