How many significant figures are present in the measurement 0.020 km?

• A. 2
• B. 4
• C. 1
• D. 3

Answer: (D)

Verified step by step guidance

1. Identify the digits in the measurement 0.020 km. The number consists of the digits 0, 0, 2, and 0.
2. Recall the rules for significant figures: Leading zeros (zeros before the first nonzero digit) are not significant; they only indicate the position of the decimal point.
3. In 0.020, the first two zeros are leading zeros and are not significant. The digits '2' and the trailing zero after it are significant because trailing zeros after a decimal point count as significant.
4. Therefore, count the significant digits: the '2' and the trailing '0' after it are significant, plus the zero immediately after the decimal point that is not leading (in this case, the zero after the 2 is significant).
5. Conclude that the measurement 0.020 km has 3 significant figures.