Assertion :Solubility of noble gases in water decreases with increases in atomic size
Reason :Solubility of noble gases in water is due to instantaneous dipole induced dipole interaction

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "the solubility of noble gases in water decreases with increases in atomic size."

- **Analysis**: Noble gases are known to be nonpolar and their solubility in water is influenced by their atomic size. As we move down the group from helium to radon, the atomic size increases. Generally, larger noble gas atoms have a greater polarizability, which can enhance their solubility in polar solvents like water.

### Step 2: Understand the Reason
The reason given is "the solubility of noble gases in water is due to instantaneous dipole-induced dipole interaction."

- **Analysis**: This statement is true. The solubility of noble gases in water is indeed due to the instantaneous dipole-induced dipole interactions. When a noble gas atom approaches a polar water molecule, it can induce a dipole in the water molecule, allowing for some solubility.

### Step 3: Compare Assertion and Reason
- The assertion claims that solubility decreases with increasing atomic size, which contradicts the general trend observed in noble gases. In fact, as atomic size increases, the solubility tends to increase due to greater polarizability.
- The reason provided is true, but it does not correctly explain the assertion since the assertion itself is incorrect.

### Conclusion
- The assertion is **false** because solubility increases with atomic size, not decreases.
- The reason is **true** as it accurately describes the nature of interactions that lead to solubility.

### Final Answer
Since the assertion is false and the reason is true, the correct option is:
**Option 3: Assertion is true but reason is false.**