Assertion : Atomicity of `O_(3)` is 3.
Reason : 1 mole of an element contains `6.022 xx 10^(23)` atoms.

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 evaluate the assertion and reason provided.

### Step 1: Understanding Atomicity
- **Definition**: Atomicity refers to the number of atoms present in a molecule.
- **For O₃**: The molecule O₃ (ozone) consists of 3 oxygen atoms. Therefore, the atomicity of O₃ is 3.

### Step 2: Evaluating the Assertion
- **Assertion**: "Atomicity of O₃ is 3."
- **Conclusion**: This statement is true because O₃ is made up of 3 oxygen atoms.

### Step 3: Understanding the Reason
- **Reason**: "1 mole of an element contains 6.022 x 10²³ atoms."
- **Explanation**: This statement refers to Avogadro's number, which indicates that 1 mole of any substance contains approximately 6.022 x 10²³ entities (atoms, molecules, etc.). This is a fundamental concept in chemistry.

### Step 4: Evaluating the Reason
- **Conclusion**: The reason is also true. It correctly states the number of atoms in 1 mole of an element.

### Step 5: Conclusion
- Both the assertion and the reason are true. However, the reason does not directly explain the assertion about the atomicity of O₃. The assertion stands alone as a fact about the molecule, while the reason provides general information about moles.

### Final Answer
- **Assertion**: True
- **Reason**: True
- **Relationship**: The reason does not support the assertion.