Question 1

Which of the following statements best describes a compound?

Accepted Answer

A substance composed of two or more elements chemically combined in a fixed ratio.

Question 2

Which of the following is an example of an ionic bond?

Accepted Answer

The bond between sodium and chlorine in $$\mathrm{NaCl}.$$

Question 3

A student measures the mass of a metal block as $$45.67\ \mathrm{g}$$ and its volume as $$12.3\ \mathrm{cm^3$}. $$What is the density of the metal, reported with the correct number of significant figures?

Accepted Answer

$$3.71\ \mathrm{g/cm^3$}$$

Question 4

Which of the following best explains why water ($$\mathrm{H_2O}) is $$classified as a pure substance?

Accepted Answer

It has a fixed composition and distinct chemical properties.

Question 5

Which SI unit would be most appropriate to measure the amount of a chemical substance used in a reaction?

Accepted Answer

Mole

Question 6

A chemist needs to prepare $$250.0\ \mathrm{mL} of a $$solution. Which measurement contains the correct number of significant figures?

Accepted Answer

$$250.0\ \mathrm{mL}$$

Question 7

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements are arranged by increasing atomic number.

Question 8

A sample of gas has a mass of $$0.850\ \mathrm{g}$$ and occupies a volume of $$0.500\ \mathrm{L}. $$What is its density in $$\mathrm{g/L}$$?

Accepted Answer

$$1.70\ \mathrm{g/L}$$

Question 9

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element contains only one type of atom, while a compound contains two or more elements chemically combined.

Question 10

Which of the following is a real-life example of a covalent bond?

Accepted Answer

The bond between hydrogen and oxygen in water.

Question 11

A student records the following measurements: $$2.50\ \mathrm{g}$$, $$2.5\ \mathrm{g}$$, $$2.500\ \mathrm{g}$$, and $$2.5000\ \mathrm{g}. $$Which measurement has the greatest number of significant figures?

Accepted Answer

$$2.5000\ \mathrm{g}$$

Question 12

Which of the following best describes the location of electrons in an atom?

Accepted Answer

Electrons orbit the nucleus in defined energy levels.

Question 13

A hospital stores oxygen gas in a tank with a mass of $$15.0\ \mathrm{kg}$$ and a volume of $$12.0\ \mathrm{L}. $$What is the density of the oxygen gas in $$\mathrm{kg/L}$$?

Accepted Answer

$$1.25\ \mathrm{kg/L}$$

Question 14

Which of the following is NOT an SI base unit?

Accepted Answer

Gram

Question 15

Which of the following best explains why carbon dioxide ($$\mathrm{CO_2$}) is $$considered a compound?

Accepted Answer

It contains two or more elements chemically combined in a fixed ratio.

Question 16

A laboratory technician needs to convert a temperature of $$25.0\ ^\circ\mathrm{C} to $$kelvin. What is the correct temperature in kelvin?

Accepted Answer

$$298.15\ \mathrm{K}$$

Question 17

Which of the following best describes the difference between a solid and a gas?

Accepted Answer

A solid has a definite shape and volume, while a gas has neither.

Question 18

Which of the following is the correct formula for density?

Accepted Answer

$$d = \dfrac{m}{V}$$

Question 19

Which of the following best describes the role of neutrons in an atom?

Accepted Answer

Neutrons contribute to the mass of the atom and reside in the nucleus.

Question 20

A sample contains $$3.0\ \mathrm{mol} of a $$substance. Which SI unit is used to express this quantity?

Accepted Answer

Mole

Matter and Measurements: Foundations of General Chemistry

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