The number of significant figures in all the given numbers 25.12, 2009, 4.156 and `1.217 × 10^(–4)` is

Options

A. `1`
B. `2`
C. `3`
D. `4`

Answer

To determine the number of significant figures in the given numbers, we will analyze each number based on the rules of significant figures.

### Step-by-Step Solution:

1. **Identify Significant Figures in 25.12:**
- The number 25.12 consists of the digits 2, 5, 1, and 2.
- According to the rules of significant figures, all non-zero digits are considered significant.
- Therefore, the number of significant figures in 25.12 is **4**.

2. **Identify Significant Figures in 2009:**
- The number 2009 consists of the digits 2, 0, 0, and 9.
- The zeros between non-zero digits (the two zeros in this case) are considered significant.
- Thus, the number of significant figures in 2009 is also **4**.

3. **Identify Significant Figures in 4.156:**
- The number 4.156 consists of the digits 4, 1, 5, and 6.
- Again, all non-zero digits are significant.
- Therefore, the number of significant figures in 4.156 is **4**.

4. **Identify Significant Figures in 1.217 × 10^(–4):**
- The number in scientific notation is 1.217.
- When counting significant figures in scientific notation, we only consider the digits in the coefficient (1.217) and ignore the exponent.
- The digits 1, 2, 1, and 7 are all significant.
- Thus, the number of significant figures in 1.217 × 10^(–4) is **4**.

### Summary of Significant Figures:
- 25.12: 4 significant figures
- 2009: 4 significant figures
- 4.156: 4 significant figures
- 1.217 × 10^(–4): 4 significant figures

### Final Answer:
All the given numbers have **4 significant figures**.

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