1. Check each statement one by one.

2. Option A: Kirchhoff’s second law represents energy conservation.

Kirchhoff’s second law (loop law) states that the algebraic sum of potential differences in any closed loop is zero:

$\sum \Delta V = 0$

This is a direct consequence of conservation of energy.

So, A is true.

3. Option B: Wheatstone bridge is the most sensitive when all the four resistances are of the same order of magnitude.

For maximum sensitivity of a Wheatstone bridge, the resistances in all four arms should be comparable, ideally of the same order.

So, B is true.

4. Option C: In a balanced Wheatstone bridge if the cell and the galvanometer are exchanged, the null point is disturbed.

A Wheatstone bridge is balanced when:

$\frac{P}{Q} = \frac{R}{S}$

In a balanced bridge, no current flows through the galvanometer branch. A standard property of the Wheatstone bridge is that interchanging the cell and galvanometer does not affect the balance condition.

So the null point is not disturbed.

Hence, C is false.

5. Option D: A rheostat can be used as a potential divider.

A rheostat is a variable resistor. If used with proper terminals, it can function as a variable potential divider.

So, D is true.

6. Conclusion

The false statement is:

$\boxed{\text{C}}$

7. Comparison with stored correct answer

Stored correct answer = C

Our derived answer = C

They match.