Significant Figures in Unit Conversions

How many significant figures should be used when converting 12.34 grams of a substance to moles?

• 3 significant figures

• 4 significant figures

• 5 significant figures

• 2 significant figures

Answer explanation

When converting 12.34 grams to moles, the number of significant figures in the original measurement determines the result. Since 12.34 has 4 significant figures, the conversion should also use 4 significant figures.

If you have 0.00560 moles of a compound, how many significant figures should the mass in grams have?

• 1 significant figures

• 2 significant figures

• 3 significant figures

• 4 significant figures

Answer explanation

The number 0.00560 has 3 significant figures (5, 6, and the trailing 0). Therefore, the mass in grams should also be reported with 3 significant figures to maintain consistency in precision.

When converting 0.0450 grams to moles, how many significant figures should the result have?

• 1 significant figure

• 2 significant figures

• 3 significant figures

• 4 significant figures

Answer explanation

The number 0.0450 grams has 3 significant figures: the '4' and '5' are significant, and the trailing '0' after the decimal point is also significant. Therefore, when converting to moles, the result should retain 3 significant figures.

Why is it important to maintain significant figures in chemical calculations?

• To ensure precision and accuracy

• To reduce the number of calculations

• To make calculations easier

• To avoid using a calculator

Answer explanation

Maintaining significant figures in chemical calculations is crucial to ensure precision and accuracy. It reflects the certainty of measurements and helps avoid misleading results, making the data reliable for scientific analysis.

What is the rule for significant figures when multiplying or dividing measurements?

• Use the most significant figures

• Use the average number of significant figures

• Use the least number of significant figures

• Use the highest number of significant figures

Answer explanation

When multiplying or dividing measurements, the result should have the same number of significant figures as the measurement with the least number of significant figures. Therefore, the correct choice is to use the least number of significant figures.