A lab sample has a mass of 3.5680 × 102 grams. What is the number of significant figures in this mass?

A. 2
Incorrect. The exponent does not tell the number of significant figures.

B. 4
Incorrect. All of the digits in the coefficient of scientific notation are significant.

C. 5
Correct! Five is the number of digits in the coefficient.

D. 7
Incorrect. The number of digits in the coefficient is the number of significant figures.

A student attempts to calculate the density of an unknown solid through repeated trials. The student’s data is in the table below.

Trial #
Mass (g)
Volume (mL)
Density (g/mL)
1
14.21
6.25
2.2736
2
14.20
6.25
2.272
3
14.16
6.23
2.27287319
4
14.27
6.28
2.27229299
5
14.30
6.29
2.27344992

What is the density of the solid to the correct number of significant figures?

A. 2 g/mL
Incorrect. The calculation cannot be more or less precise than the least precise measurement.

B. 2 3 g/mL
Incorrect. The calculation cannot be more or less precise than the least precise measurement.

C. 2.27 g/mL
Correct! The number of significant figures in the least precise measurement, volume, is 3. Therefore, the final calculation should have 3 significant figures.

D. 2.268 g/mL
Incorrect. The calculation cannot be more or less precise than the least precise measurement.

The temperature of a solution is  16.02°C. How many significant figures are there in the recorded temperature?

A. 4 significant figures
Correct! The measurement 16.02°C; all 4 digits would be considered significant.

B. 3 significant figures
Incorrect. The measurement 16.02°C; all 4 digits would be considered significant. The zero is significant because it falls between two non-zero digits.

C. 2 significant figures
Incorrect. The measurement 16.02°C; all 4 digits would be considered significant. The zero is significant because it falls between two non-zero digits.

D. 1 significant figure
Incorrect. The measurement 16.02°C; all 4 digits would be considered significant. The zero is significant because it falls between two non-zero digits.

Maggie started an experiment with 100.5 L of concentrated hydrochloric acid; 0.221 L is used during the experiment. What is the volume of the unused hydrochloric acid with the correct number of significant figures?

A. 100.279 L
Incorrect. Since this is a subtracting problem, the answer would only have as many decimal places as the least accurate measurement in the original problem.

B. 100.28 L
Incorrect. Since this is a subtracting problem, the answer would only have as many decimal places as the least accurate measurement in the original problem.

C. 100.3 L
Correct! Since this is a subtracting problem, the answer would only have as many decimal places as the least accurate measurement in the original problem.

D. 100 L
Incorrect. Since this is a subtracting problem, the answer would only have as many decimal places as the least accurate measurement in the original problem.

An atom of gold has a mass of 3.2706 × 10–22 g. How many significant figures are in this value?

A. 2
Incorrect. All the digits in the coefficient of a number written in scientific notation are significant.

B. 3
Incorrect. All the digits in the coefficient of a number written in scientific notation are significant.

C. 4
Incorrect. All the digits in the coefficient of a number written in scientific notation are significant.

D. 5
Correct! All the digits in the coefficient of a number written in scientific notation are significant.