Units And Measurement

Answer (c)

Step 1: Rules for significant figures
- All non-zero digits are significant.
- Zeros between non-zero digits are significant.
- Leading zeros (before the first non-zero digit) are not significant.
- Trailing zeros in a decimal number are significant if explicitly shown.

Step 2: Analyze the number 0.00456
Write the number: 0.00456
- Leading zeros: 0.004 (these are not significant).
- Non-zero digits: 4, 5, 6 (all are significant).
- There are no trailing zeros after the decimal point in this case.
So, the significant figures are: 4, 5, 6.
Total: 3 significant figures.