Q: Which of the following calculations is reported with the correct number of significant figures?

$$5.00 \times 2.000 + 0.65 = 10.7$$

Question 1

A laboratory technician measures the mass of a sample as 12.3 g and its volume as 4.56 mL. What is the density of the sample, reported with the correct number of significant figures?

Accepted Answer

$$2.70 g/mL$$

Question 2

Which of the following statements about significant figures is TRUE?

Accepted Answer

When adding or subtracting, the result should be rounded to the same number of decimal places as the value with the fewest decimal places.

Question 3

A cube of gold has a side length of $$2.00 cm. If $$the density of gold is $$19.3 g/cm$^3$$, what is the mass of the cube, reported with the correct number of significant figures?

Accepted Answer

$$154 g$$

Question 4

A car uses gasoline at a rate of $$16.0 L/100 km. $$Convert this to miles per gallon (mpg). Use the conversion factors: $$1$$ mile $$= 1.609 km$$, $$1$$ gallon $$= 3.785 L. $$Report your answer with the correct number of significant figures.

Accepted Answer

$$14.7$$ mpg

Question 5

Which of the following best explains why conversion factors do not limit the number of significant figures in a calculation?

Accepted Answer

Conversion factors are defined values and considered to have infinite significant figures.

Question 6

Calculate $$0.378 mL$$ $$+ 42.3 mL$$ $$- 1.5833 mL $$and report the answer with the correct number of significant figures.

Accepted Answer

$$41.1 mL$$

Question 7

A student multiplies $$10.12 by$$ $$4$$ and gets $$40.48. $$How should this result be reported with the correct number of significant figures?

Accepted Answer

$$40$$

Question 8

A scientist adds $$170.4 lb $$and $$0.07 lb. $$What is the correct way to report the sum?

Accepted Answer

$$170.5 lb$$

Question 9

Which of the following calculations is reported with the correct number of significant figures?

Accepted Answer

$$5.00 	imes 2.000 + 0.65 = 10.7$$

Question 10

A cube of silver has a side length of $$0.85 m. $$The density of silver is $$10.5 g/cm$^3. $$What is the mass of the cube in kg, reported with the correct number of significant figures? ($$1 m$$ $$= 100 cm$$, $$1 kg$$ $$= 1000 g)$$

Accepted Answer

$$6.4 	imes 10^3$ kg

Question 11

Which of the following is the correct rule for reporting the result of an addition or subtraction calculation?

Accepted Answer

Report the answer down to the highest digit that contains uncertainty among the values used.

Question 12

A student calculates $$365 \div 12$$ and gets $$30.41666.... $$How should this result be reported with the correct number of significant figures?

Accepted Answer

$$30$$

Question 13

Why is it important to identify the number of significant figures in measured values before performing calculations?

Accepted Answer

To ensure the calculated result does not have more significant figures than the least precise measurement.

Question 14

Which of the following is NOT a correct statement about significant figures?

Accepted Answer

Calculated values can have more significant figures than the measured values used in the calculation.

Question 15

A student is converting $$1.00 m$^3 to cm$^3. $$Which of the following is the correct conversion?

Accepted Answer

$$1.00 	imes 10^6$ cm^3$

Question 16

A patient receives a medication dose of $$0.250 g. $$The medication is supplied as $$50.0 mg/mL. $$How many mL should the patient receive? Report your answer with the correct number of significant figures.

Accepted Answer

$$5.00 mL$$

Question 17

A chemist records the following measurements: $$2.345 g$$, $$0.07 g$$, and $$1.2 g. $$What is the sum, reported with the correct number of significant figures?

Accepted Answer

$$3.6 g$$

Question 18

Which of the following best describes the effect of rounding in reporting calculated values?

Accepted Answer

Rounding ensures that the reported value does not imply greater precision than the measurements allow.

Question 19

A student multiplies $$0.12 by$$ $$4$$ and gets $$0.48. $$How many significant figures should the answer have?

Accepted Answer

One

Question 20

A solution is prepared by mixing $$25.0 mL of $$water with $$13.45 mL of $$ethanol. What is the total volume, reported with the correct number of significant figures?

Accepted Answer

$$38.5 mL$$

Rounding Numbers, Significant Figures, and Unit Conversion in Chemistry

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