Which of the following measurements contains two significant figures?

• A. 0.030
• B. 0.0045
• C. 100
• D. 2.5

Answer: (D)

Verified step by step guidance

1. Review the rules for counting significant figures: all nonzero digits are significant; zeros between nonzero digits are significant; leading zeros are not significant; trailing zeros in a decimal number are significant.
2. Analyze the first measurement, 0.030: the leading zeros are not significant, but the zero after the 3 is a trailing zero in a decimal number, so it counts as significant. Therefore, 0.030 has two significant figures.
3. Analyze the second measurement, 0.0045: the leading zeros are not significant, and the digits 4 and 5 are nonzero, so this number has two significant figures.
4. Analyze the third measurement, 100: without a decimal point, trailing zeros are not considered significant, so this number has only one significant figure.
5. Compare the options and identify which measurements have exactly two significant figures based on the above analysis.