A small amount of calcium oxide (quick lime) is taken in a beaker. Water is slowly added to this. Which of the following observations is/are incorrect about this activity ?
(i) The beaker becomes hot because it is an endothermic reaction.
(ii) A clear solution is obtained at the top after the reaction gets over.
(iii) This reaction is a combination reaction in which quick lime `(CaO)` is converted into slaked lime, `Ca(OH)_2`

Options

A. (i), (ii) and (iii)
B. (ii) and (iii) only
C. (i) only
D. (i) and (iii) only

Explanation

To solve the question regarding the observations made during the reaction of calcium oxide (quick lime) with water, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- When calcium oxide (CaO) is added to water, it reacts to form calcium hydroxide (Ca(OH)₂), also known as slaked lime.
- The reaction can be represented as:
\[ \text{CaO} + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 \]

2. **Observation of Heat**:
- This reaction is exothermic, meaning it releases heat.
- Therefore, the statement "The beaker becomes hot because it is an endothermic reaction" is incorrect. The beaker becomes hot due to the exothermic nature of the reaction.

3. **Clarity of the Solution**:
- After the reaction, calcium hydroxide dissolves in water to form a clear solution, known as limewater.
- Thus, the statement "A clear solution is obtained at the top after the reaction gets over" is correct.

4. **Type of Reaction**:
- The reaction between calcium oxide and water is indeed a combination reaction, where two reactants combine to form a single product (Ca(OH)₂).
- Therefore, the statement "This reaction is a combination reaction in which quick lime (CaO) is converted into slaked lime (Ca(OH)₂)" is also correct.

### Summary of Observations:
- (i) Incorrect: The beaker becomes hot because it is an **exothermic** reaction, not endothermic.
- (ii) Correct: A clear solution is obtained after the reaction.
- (iii) Correct: This is a combination reaction.

### Final Conclusion:
The incorrect observation is (i). The correct observations are (ii) and (iii).

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