Question 1

Which of the following best describes a significant figure in a measured value?

Accepted Answer

Any digit that is certain, plus one final digit that has been estimated and contains uncertainty.

Question 2

A student measures the length of a desk using two rulers: Ruler A with divisions every 1 cm, and Ruler B with divisions every 0.1 cm. Which statement is correct regarding the uncertainty in the measurements?

Accepted Answer

Measurement with Ruler B has less uncertainty because it allows estimation to a finer division.

Question 3

Which of the following numbers contains exactly three significant figures?

Accepted Answer

$$0.00450$$

Question 4

When adding $$15.346$$ and $$2.70$$, what is the correct answer with the proper number of significant figures?

Accepted Answer

$$18.0$$

Question 5

Which of the following statements about trailing zeros is correct?

Accepted Answer

Trailing zeros in a number with a decimal point are significant.

Question 6

A student records a measurement as $$25.00 mL. $$Which statement best explains the number of significant figures?

Accepted Answer

There are four significant figures because all digits, including trailing zeros after the decimal, are significant.

Question 7

Suppose you combine $$11.5 mL of $$water (measured with a graduated cylinder) and $$10.00 mL of $$water (measured with a buret). What is the correct total volume, reported with the proper uncertainty?

Accepted Answer

$$21.5 mL$$

Question 8

Which of the following numbers has an ambiguous number of significant figures and should be written in scientific notation to clarify?

Accepted Answer

$$200$$

Question 9

When multiplying $$0.054 by$$ $$0.000954$$, how many significant figures should the answer have?

Accepted Answer

Two

Question 10

Which of the following is an example of an exact number in chemistry?

Accepted Answer

The number of students in a classroom.

Question 11

A student calculates $$(6.543 - 6.4790)$$ for a lab result. What is the correct answer with the proper number of significant figures?

Accepted Answer

$$0.064$$

Question 12

Which of the following best describes the rule for significant figures in multiplication and division?

Accepted Answer

The answer should have the same number of significant figures as the number with the fewest significant figures.

Question 13

Calculate the percent error if the experimental value of molar mass is $$12.82$$ and the theoretical value is $$12.53$$, reporting your answer to the correct number of significant figures. Use the formula: $$\%	ext{ error} = \frac{|	ext{theoretical} - 	ext{experimental}|}{	ext{theoretical}} 	imes 100$$

Accepted Answer

$$2.3\%$$

Question 14

Which of the following measurements contains only one digit of uncertainty?

Accepted Answer

$$21.50 mL$$

Question 15

When performing the calculation $$3.567 - 3.1263 + 10.193$$, what is the correct number of decimal places in the final answer?

Accepted Answer

Two decimal places

Question 16

Which of the following is NOT a significant figure in the number $$0.00560$$?

Accepted Answer

The zero after the decimal point and before the 5

Question 17

A student measures a sample as $$0.00320 g. $$How many significant figures does this measurement have?

Accepted Answer

Four

Question 18

Which of the following best explains why leading zeros are not significant?

Accepted Answer

They are only placeholders and do not represent measured values.

Question 19

If you measure a volume as $$100 mL $$using a graduated cylinder, which of the following best describes the uncertainty in your measurement?

Accepted Answer

The uncertainty is in the ones place.

Question 20

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

Accepted Answer

$$0.0654 / 0.000954 = 68.6$$

Measurement, Uncertainty, and Significant Figures in Chemistry

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