Assertion (A): In curing cement plasters, water is sprinkled form time to time.
Reason (R ): It converts sand into silicic acid.

Options

A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`.
B. If both `(A)` and `(R )` are correct, but `(R )` is not the correct explanation of `(A)`.
C. If `(A)` is correct, but `(R )` is incorrect.
D. If `(A)` is incrrect, but `(R )` is correct.

Explanation

To analyze the assertion and reason provided in the question, we can break it down into steps:

### Step 1: Understand the Assertion
The assertion states that "In curing cement plasters, water is sprinkled from time to time."
- This is a common practice in construction. Water is essential for the curing process of cement as it helps in the hydration of the cement compounds.

### Step 2: Understand the Reason
The reason states that "It converts sand into silicic acid."
- This statement is misleading. Sand is primarily composed of silicon dioxide (SiO2) and does not convert into silicic acid through the curing process.

### Step 3: Analyze the Curing Process
During the curing of cement:
- Water is added to facilitate the hydration of cement compounds, particularly calcium silicates and calcium aluminates.
- The hydration process leads to the formation of hydrated silicate crystals, which strengthen the cement.

### Step 4: Conclusion
- The assertion is true because water is indeed sprinkled during the curing of cement plasters.
- The reason is false because the curing process does not convert sand into silicic acid; rather, it involves the hydration of cement components.

### Final Answer
- The assertion is true, but the reason is false.