correct 0.007985 to three significant figures.

Analyze the question: We need to round 0.007985 to three significant figures.

Concept: Significant figures start counting from the first non-zero digit. Leading zeros (the zeros after the decimal point and before the first non-zero digit) are not significant.

Solution:

1. Write the number: 0.007985
2. Leading zeros: 0.00 are not significant.
3. The significant digits are 7, 9, 8, 5.
4. For three significant figures, keep 7, 9, 8 and look at the next digit, which is 5.
5. Since the next digit is 5, we round up the last kept digit: 8 becomes 9.

0.007985 ≈ 0.00799

Check the other options:

• A. 0.0109 is far too large, so it is wrong.
• B. 0.0800 is wrong because it changes the size of the number.
• D. 0.008 is only 1 significant figure, so it does not meet the requirement.

Tip: Always start counting significant figures from the first non-zero digit. When the digit after your cut-off is 5 or more, round up. Don't forget to keep the zeros in front as place holders (0.00799, not 0.799).