In which of the following numbers all zeros are significant ?

Options

A. 0.0007
B. 0.007
C. 70
D. 0.7

Answer

To determine which of the given numbers has all zeros as significant figures, we need to understand the rules of significant figures, particularly regarding zeros. Here’s a step-by-step solution:

### Step 1: Identify the Numbers
Let's assume the numbers provided in the options are:
1. 0.007
2. 0.070
3. 0.700
4. 0.7

### Step 2: Analyze Each Number
1. **0.007**:
- The zeros are leading zeros (before the first non-zero digit).
- Leading zeros are not significant.
- **Significant Figures**: 1 (only the '7' is significant).

2. **0.070**:
- The first two zeros are leading zeros, and the '7' is a non-zero digit.
- The zero after '7' is a trailing zero in a decimal number, which is significant.
- **Significant Figures**: 2 (the '7' and the '0' after it).

3. **0.700**:
- The first zero is a leading zero, while the '7' is a non-zero digit.
- The two zeros after '7' are trailing zeros in a decimal number, which are significant.
- **Significant Figures**: 3 (the '7' and both '0's).

4. **0.7**:
- The zero is a leading zero.
- **Significant Figures**: 1 (only the '7' is significant).

### Step 3: Conclusion
From the analysis:
- The number **0.700** has all zeros (the two zeros after '7') counted as significant figures.
- Therefore, the answer is **0.700**.

### Final Answer
The number in which all zeros are significant is **0.700**.

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