Question 1

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Ice has a lower density than liquid water because its molecules are more loosely packed.

Question 2

A chemist needs to separate a mixture of ethanol and water. Which method would be most appropriate and why?

Accepted Answer

Distillation, because ethanol and water have different boiling points.

Question 3

Which of the following is an example of a homogeneous mixture?

Accepted Answer

Air

Question 4

A sample of gas has a mass of $$2.50\ \mathrm{g}$$ and occupies a volume of $$1.00\ \mathrm{L}. $$What is its density?

Accepted Answer

$$2.50\ \mathrm{g/L}$$

Question 5

Which of the following statements about compounds is correct?

Accepted Answer

Compounds can be broken down into elements by chemical processes.

Question 6

Which process is illustrated by the separation of a mixture of sand and salt water using a funnel and filter paper?

Accepted Answer

Filtration

Question 7

Which of the following is a physical change?

Accepted Answer

Melting ice

Question 8

A student mixes oil and water in a beaker. After a few minutes, two separate layers form. This mixture is best described as:

Accepted Answer

A heterogeneous mixture

Question 9

Which of the following best describes a pure substance?

Accepted Answer

A material with constant composition and unique properties

Question 10

Which of the following is NOT a property of gases compared to solids and liquids?

Accepted Answer

Gases have a fixed volume.

Question 11

A solution of salt in water is best classified as:

Accepted Answer

A homogeneous mixture

Question 12

Which of the following is an example of a chemical change?

Accepted Answer

Electrolysis of water to form hydrogen and oxygen gases

Question 13

Which of the following best describes an element?

Accepted Answer

A substance that cannot be decomposed into simpler substances by chemical means

Question 14

A sample of a liquid has a mass of $$25.0\ \mathrm{g}$$ and a volume of $$20.0\ \mathrm{mL}. $$What is its density?

Accepted Answer

$$1.25\ \mathrm{g/mL}$$

Question 15

Which of the following is a correct statement about homogeneous mixtures?

Accepted Answer

They are also called solutions.

Question 16

Which of the following is a real-world application of density?

Accepted Answer

Testing ethylene glycol to water ratios in car radiators

Question 17

Which of the following best describes the process of distillation?

Accepted Answer

Separation of components based on differences in boiling points

Question 18

Which of the following is NOT a physical property?

Accepted Answer

Ability to rust

Question 19

A mixture of gasoline and water is left to stand. Two layers form. Which statement is true?

Accepted Answer

This is a heterogeneous mixture because the layers are distinguishable.

Question 20

Which of the following best describes a chemical process?

Accepted Answer

A process in which a substance becomes a new substance with different properties and composition

Fundamental Concepts of Matter, Mixtures, and Separation Techniques in General Chemistry

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