Q: Which of the following is the correct formula for percent error?

$$\frac{\lvert \text{experimental value} - \text{accepted value} \rvert}{\text{accepted value}} \times 100\%$$

Question 1

Which of the following best describes the purpose of using significant figures in scientific measurements?

Accepted Answer

To indicate the precision of a measurement and reflect the certainty in the reported data.

Question 2

A student measures the mass of a sample three times and records the values: 12.34 g, 12.36 g, and 12.35 g. The accepted value is 12.50 g. Which statement best describes the accuracy and precision of these measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is the correct way to express 0.000456 in scientific notation?

Accepted Answer

$$4.56 	imes 10$$^{-4}$$

Question 4

A graduated cylinder contains 25.0 mL of water. After adding a metal object, the water level rises to 32.5 mL. What is the volume of the metal object?

Accepted Answer

$$7.5\ \mathrm{mL}$$

Question 5

Which of the following conversion factors would you use to convert 5.0 kilometers to meters?

Accepted Answer

$$\frac{1000\ \mathrm{m}}{1\ \mathrm{km}}$$

Question 6

A thermometer reads $$22.0\ ^\circ\mathrm{C}. $$What is this temperature in Kelvin?

Accepted Answer

$$295.2\ \mathrm{K}$$

Question 7

Which of the following best explains why the metric system is preferred in scientific measurements?

Accepted Answer

It is based on multiples of ten, making conversions straightforward.

Question 8

A student calculates the density of a liquid as $$0.789\ \mathrm{g/mL}$$ using a mass of $$15.78\ \mathrm{g}$$ and a volume of $$20.0\ \mathrm{mL}. $$Which of the following best describes the calculation?

Accepted Answer

The student divided mass by volume: $$\frac{15.78\ \mathrm{g}}{20.0\ \mathrm{mL}} = 0.789\ \mathrm{g/mL}$$

Question 9

Which of the following measurements is the most precise?

Accepted Answer

$$12.345\ \mathrm{g}$$

Question 10

A laboratory procedure requires you to dilute a $$6.0\ \mathrm{M}$$ solution to $$1.0\ \mathrm{M}$$ using distilled water. If you need $$100\ \mathrm{mL} of $$the final solution, how much of the $$6.0\ \mathrm{M}$$ solution should you use?

Accepted Answer

$$16.7\ \mathrm{mL}$$

Question 11

Which of the following is NOT a base SI unit?

Accepted Answer

Liter ($$\mathrm{L})$$

Question 12

A sample of gas has a mass of $$2.50\ \mathrm{g}$$ and occupies a volume of $$1.25\ \mathrm{L}. $$What is the density of the gas?

Accepted Answer

$$2.00\ \mathrm{g/L}$$

Question 13

Which of the following best describes the difference between accuracy and precision?

Accepted Answer

Accuracy refers to how close a measurement is to the true value, while precision refers to how close repeated measurements are to each other.

Question 14

Convert $$350\ \mathrm{K} to $$degrees Celsius.

Accepted Answer

$$76.85\ ^\circ\mathrm{C}$$

Question 15

A student needs to prepare $$250\ \mathrm{mL} of a$$ $$0.50\ \mathrm{M}$$ NaCl solution. How many moles of NaCl are required?

Accepted Answer

$$0.125\ \mathrm{mol}$$

Question 16

Which of the following is the correct order of metric prefixes from largest to smallest?

Accepted Answer

kilo-, centi-, milli-

Question 17

A solution is labeled as $$0.250\ \mathrm{g/mL}. $$What is the mass of $$40.0\ \mathrm{mL} of $$this solution?

Accepted Answer

$$10.0\ \mathrm{g}$$

Question 18

Which of the following best explains why it is important to use the correct number of significant figures in calculations?

Accepted Answer

To accurately reflect the precision of the measurements used in the calculation.

Question 19

A student records a measurement as $$0.0700\ \mathrm{g}. $$How many significant figures does this measurement have?

Accepted Answer

3

Question 20

Which of the following is the correct formula for percent error?

Accepted Answer

$$\frac{\lvert 	ext{experimental value} - 	ext{accepted value} vert}{	ext{accepted value}} 	imes 100\%$$

Scientific Measurements and Calculations: Fundamentals of Chemistry (Chapter 2)

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