Assertion (A): The reaction of Cl with cold dilute and hot conc. NaOH is disproportionation reaction
Reason R: Cl forms zero oxidation state change to -1 & +1 in cold dilute condition and -1 & +5 in hot concentrated condition

Options

A. A & R are is correct explanation of A
B. A & R are true, R is not correct explanation of A
C. A is true, but R is false
D. A is false, but R is true

Explanation

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

### Step-by-Step Solution:

1. **Understanding Disproportionation Reaction**:
- A disproportionation reaction is a type of redox reaction where a single substance is both oxidized and reduced, resulting in the formation of two different products with different oxidation states of the same element.

**Hint**: Remember that in a disproportionation reaction, one species undergoes both oxidation and reduction.

2. **Analyzing the Assertion**:
- The assertion states that the reaction of Cl with cold dilute and hot concentrated NaOH is a disproportionation reaction.
- We will examine the reactions of chlorine with both cold dilute NaOH and hot concentrated NaOH to verify this.

3. **Reaction of Cl with Cold Dilute NaOH**:
- The balanced reaction is:
\[ Cl_2 + 2NaOH \rightarrow NaCl + NaOCl + H_2O \]
- In this reaction, the oxidation states of chlorine are:
- In \(Cl_2\): 0 (elemental state)
- In \(NaCl\): -1 (Cl is reduced)
- In \(NaOCl\): +1 (Cl is oxidized)
- Thus, chlorine goes from 0 to -1 and +1, indicating that it is both oxidized and reduced.

**Hint**: Check the oxidation states of chlorine in each compound formed to confirm the changes.

4. **Reaction of Cl with Hot Concentrated NaOH**:
- The balanced reaction is:
\[ Cl_2 + 6NaOH \rightarrow 5NaCl + NaClO_3 + 3H_2O \]
- In this reaction, the oxidation states of chlorine are:
- In \(Cl_2\): 0
- In \(NaCl\): -1 (Cl is reduced)
- In \(NaClO_3\): +5 (Cl is oxidized)
- Thus, chlorine goes from 0 to -1 and +5, again indicating that it is both oxidized and reduced.

**Hint**: Ensure to balance the reaction correctly and track the oxidation states of chlorine in each product.

5. **Conclusion**:
- Since in both reactions, chlorine undergoes a change in oxidation state where it is both oxidized and reduced, we confirm that the assertion is correct.
- The reason provided is also correct as it accurately describes the changes in oxidation states of chlorine in both reactions.

6. **Final Answer**:
- Both the assertion (A) and the reason (R) are correct, and the reason correctly explains the assertion.

### Summary:
- **Assertion (A)**: Correct
- **Reason (R)**: Correct