Q: Which of the following numbers, when written in scientific notation, shows only the significant digits?

$$0.000560 as$$ $$5.60 \times 10$$^{-4}$$

Question 1

Which of the following numbers contains exactly three significant figures?

Accepted Answer

$$0.00450$$

Question 2

A student measures the mass of a sample and records it as $$0.0700 g. $$How many significant figures are in this measurement?

Accepted Answer

$$4$$

Question 3

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

Accepted Answer

There are $$12$$ eggs in a dozen.

Question 4

Which of the following numbers has only one significant figure?

Accepted Answer

$$0.00040$$

Question 5

A laboratory balance gives a reading of $$0.250 g. $$Which statement best describes the last digit in this measurement?

Accepted Answer

It is an estimated digit, representing uncertainty in the measurement.

Question 6

Which of the following numbers, when written in scientific notation, shows only the significant digits?

Accepted Answer

$$0.000560 as$$ $$5.60 	imes 10$$^{-4}$$

Question 7

A student records the length of a pencil as $$15.0 cm. $$Which of the following best describes this number?

Accepted Answer

It is a measured number with three significant figures.

Question 8

Which of the following statements about zeros is correct?

Accepted Answer

Zeros at the end of a decimal number are significant.

Question 9

How many significant figures are in the measurement $$0.03050 mL$$?

Accepted Answer

$$4$$

Question 10

Which of the following is NOT an example of an exact number?

Accepted Answer

A laboratory sample has a mass of $$2.00 g.$$

Question 11

A nurse needs to convert $$1.00 L to mL $$using the definition $$1 L$$ $$= 1000 mL. $$How many significant figures should the answer have?

Accepted Answer

Three, because $$1.00 L $$has three significant figures and $$1000 mL is $$exact.

Question 12

A student writes the number $$2500 as$$ $$2.5 	imes 10^3$. How many significant figures does this number have?

Accepted Answer

$$2$$

Question 13

Which of the following best explains why $$0.0045$$ has only two significant figures?

Accepted Answer

The zeros before the $$4$$ are placeholders and not significant.

Question 14

A measurement is recorded as $$5.00 	imes 10^2$ m. How many significant figures does this number have?

Accepted Answer

$$3$$

Question 15

Which of the following best describes the difference between measured and exact numbers?

Accepted Answer

Measured numbers have uncertainty and a limited number of significant figures, while exact numbers have no uncertainty and unlimited significant figures.

Question 16

A scientist records a temperature as $$205.0 K. $$Which digit is estimated?

Accepted Answer

The last digit, $$0$$, is estimated.

Question 17

Which of the following numbers has four significant figures?

Accepted Answer

$$5.008$$

Question 18

A solution is prepared by mixing $$0.0750 L of $$water with $$0.0040 L of $$ethanol. How many significant figures are in the sum?

Accepted Answer

The answer should have two decimal places, matching the least number of decimal places in the measurements.

Question 19

A student writes $$1.250 	imes 10^6$ g. How many significant figures are in this number?

Accepted Answer

$$4$$

Question 20

Which of the following best explains why $$850,000$$ has only two significant figures?

Accepted Answer

The zeros act as placeholders and are not significant without a decimal point.

Chemistry and Measurements: Measured Numbers and Significant Figures

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