The length of a rod is measured by different instruments. Of the following the accurate result is

Options

A. 500 mm
B. 500.00 mm
C. 500.0 mm
D. 0.5 m

Answer

To determine which measurement of the rod's length is the most accurate, we need to analyze the number of significant figures in each option provided. The number of significant figures indicates the precision of the measurement, with more significant figures suggesting a more accurate measurement.

### Step-by-Step Solution:

1. **Identify the Options**:
We have four options for the length of the rod, each with a different number of significant figures:
- Option 1: 500 mm (3 significant figures)
- Option 2: 500.00 mm (5 significant figures)
- Option 3: 5000 mm (4 significant figures)
- Option 4: 5 mm (1 significant figure)

2. **Understand Significant Figures**:
Significant figures are the digits in a number that contribute to its precision. This includes all non-zero digits, any zeros between significant digits, and any trailing zeros in the decimal portion.

3. **Count Significant Figures**:
- For **Option 1 (500 mm)**: The zeros are not significant because there is no decimal point, so it has 3 significant figures.
- For **Option 2 (500.00 mm)**: All digits are significant, including the trailing zeros after the decimal point, giving it 5 significant figures.
- For **Option 3 (5000 mm)**: The zeros are not significant without a decimal point, so it has 4 significant figures.
- For **Option 4 (5 mm)**: This has only 1 significant figure.

4. **Determine the Most Accurate Measurement**:
The measurement with the highest number of significant figures is considered the most accurate because it reflects a more precise measurement. In this case, **Option 2 (500.00 mm)** has the most significant figures (5), indicating it is the most accurate measurement.

5. **Conclusion**:
Therefore, the accurate result for the length of the rod is given by **Option 2: 500.00 mm**.

### Final Answer:
The accurate result is **Option 2: 500.00 mm**.

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