A : Higher is the accuracy of measurement, if instrument have smaller least count.
R : Smaller the percentage error, higher is the accuracy of measurement.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4).

Answer

To analyze the given statements A and R, we will break down the concepts of least count, accuracy, and percentage error step by step.

### Step 1: Understanding the Assertion (A)
The assertion states that "Higher is the accuracy of measurement, if the instrument has a smaller least count."

- **Explanation**: The least count of an instrument is the smallest value that can be measured by that instrument. A smaller least count means that the instrument can measure values more precisely. Therefore, if an instrument has a smaller least count, it can provide measurements that are closer to the true value, which implies higher accuracy.

### Step 2: Understanding the Reason (R)
The reason states that "Smaller the percentage error, higher is the accuracy of measurement."

- **Explanation**: Percentage error is defined as the ratio of the error in measurement to the true value, multiplied by 100. A smaller percentage error indicates that the measurement is closer to the true value, which means higher accuracy. Thus, there is an inverse relationship between percentage error and accuracy.

### Step 3: Relationship Between Least Count, Percentage Error, and Accuracy
- If the least count is smaller, the possible error in measurement is also smaller. This leads to a smaller percentage error, which in turn indicates higher accuracy.
- Conversely, if the least count is larger, the possible error increases, leading to a larger percentage error and thus lower accuracy.

### Step 4: Conclusion
Both the assertion (A) and the reason (R) are correct. The reason correctly explains the assertion because a smaller least count leads to a smaller percentage error, which indicates higher accuracy.

### Final Answer
- Assertion (A) is correct.
- Reason (R) is correct and explains the assertion.

---