Assertion : K, Rb and Cs can also form superoxides.
Reason : Their ionic radii increase in the order `Cs^(+) lt Rb^(+) lt K^(+)`.

Options

A. Assertion and reason both are correct statements and reason is correct explanation for assertion.
B. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
C. Assertion is correct statement but reason is wrong statement.
D. Assertion is wrong statement but reason is correct statement

Answer

To solve the question regarding the assertion and reason related to the formation of superoxides by potassium (K), rubidium (Rb), and cesium (Cs), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that K, Rb, and Cs can form superoxides.
- Superoxides are compounds that contain the superoxide ion (O₂⁻).
- In group 1 of the periodic table, larger alkali metal cations (like K⁺, Rb⁺, and Cs⁺) can stabilize larger anions, such as the superoxide ion.

2. **Analyzing the Reason**:
- The reason provided states that the ionic radii increase in the order Cs⁺ < Rb⁺ < K⁺.
- However, this statement is incorrect. As we move down the group in the periodic table, the ionic radius increases due to the addition of electron shells. Therefore, the correct order should be K⁺ > Rb⁺ > Cs⁺.

3. **Conclusion on Assertion and Reason**:
- Since the assertion is true (K, Rb, and Cs can form superoxides) and the reason is false (the order of ionic radii is incorrect), we conclude that the assertion is correct while the reason is incorrect.

4. **Final Answer**:
- The correct answer is that the assertion is true and the reason is false.