Auto-oxidation of bleaching powder gives:

Options

A. only calcium chlorate
B. only calcium chloride
C. only calcium hypochlorite
D. both (a) and (b)

Explanation

To solve the question regarding the auto-oxidation of bleaching powder, we will analyze the chemical reactions involved and identify the products formed.

### Step-by-Step Solution:

1. **Identify the Composition of Bleaching Powder**:
- Bleaching powder is chemically known as calcium oxychloride and has the formula \( \text{Ca(OCl)}_2 \).

2. **Understand Auto-Oxidation**:
- Auto-oxidation refers to a process where a substance reacts with oxygen in the air, leading to the formation of new products. In the case of bleaching powder, it can react with oxygen over time.

3. **Write the Reaction**:
- The auto-oxidation of bleaching powder can be represented as follows:
\[ 2 \text{Ca(OCl)}_2 + 2 \text{H}_2\text{O} + \text{O}_2 \rightarrow 2 \text{CaCl}_2 + 2 \text{Ca(ClO}_3\text{)} + 2 \text{H}_2\text{O} \]
- In this reaction, bleaching powder reacts with water and oxygen to form calcium chloride \( \text{CaCl}_2 \) and calcium chlorate \( \text{Ca(ClO}_3\text{)}_2 \).

4. **Identify the Products**:
- From the reaction, we can see that two products are formed:
- Calcium Chlorate \( \text{Ca(ClO}_3\text{)}_2 \)
- Calcium Chloride \( \text{CaCl}_2 \)

5. **Evaluate the Options**:
- The options provided in the question were:
- A) Only calcium chlorate
- B) Only calcium chloride
- C) Only calcium hypochlorite
- D) Both A and B
- Based on the reaction, both calcium chlorate and calcium chloride are produced, making option D the correct choice.

### Final Answer:
The auto-oxidation of bleaching powder gives both calcium chlorate and calcium chloride. Therefore, the correct answer is **D) Both A and B**.