Statement-1 A lens has two principal focal lengths which may differ
because
Statement -2 : Light can fall on either surface of the lens. The two principal focal lengths differ when medium on the two sides has different refractive indices.

Options

A. Statement -1 is True, statement -2 is True, Statement -2 is a correct explanation for Statement -1.
B. Statement -1 is True, Statement -2 is True , Statement-2 is Not a correct explanation for statement-2
C. Statement -1 is True, statement -2 is False
D. Statement -1 is False, Statement -2 is True.

Answer

To solve the question, we need to analyze both statements and determine their validity along with the relationship between them.

### Step-by-Step Solution:

1. **Understanding Statement 1**:
- Statement 1 claims that a lens has two principal focal lengths that may differ. This is true. Lenses can indeed have different focal lengths depending on the medium on either side of the lens.

2. **Understanding Statement 2**:
- Statement 2 states that light can fall on either surface of the lens, and that the two principal focal lengths differ when the medium on the two sides has different refractive indices. This is also true. The refractive index of the medium surrounding the lens affects the focal length.

3. **Lens Maker's Formula**:
- The lens maker's formula is given by:
\[ \frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right) \]
where \(f\) is the focal length, \(\mu\) is the refractive index of the lens material, and \(R_1\) and \(R_2\) are the radii of curvature of the lens surfaces.
- When light falls on one surface of the lens, the focal length will depend on the refractive index of the medium on that side. If the medium on one side has a refractive index \(\mu_1\) and the other side has \(\mu_2\), the focal lengths will be different.

4. **Conclusion**:
- Since both statements are true and Statement 2 provides a correct explanation for Statement 1, we conclude that both statements are correct and that Statement 2 is the correct explanation for Statement 1.

### Final Answer:
- Both statements are true, and Statement 2 is the correct explanation for Statement 1.