Question 1

Which of the following best describes a compound?

Accepted Answer

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

Question 2

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

Accepted Answer

Saltwater

Question 3

A chemist wants to separate a mixture of sand and salt. Which method would be most appropriate?

Accepted Answer

Filtration followed by evaporation

Question 4

Which of the following statements is TRUE regarding elements and compounds?

Accepted Answer

Compounds can be broken down into elements by chemical means.

Question 5

Air is best classified as which of the following?

Accepted Answer

Homogeneous mixture

Question 6

Which of the following is NOT a pure substance?

Accepted Answer

Brass (an alloy of copper and zinc)

Question 7

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

Accepted Answer

A heterogeneous mixture

Question 8

Which of the following can be separated into its components by physical means?

Accepted Answer

Saltwater

Question 9

Which scenario best illustrates the difference between a compound and a mixture?

Accepted Answer

Mixing iron filings and sulfur, then heating the mixture to form iron sulfide.

Question 10

Which of the following is a correct statement about mixtures?

Accepted Answer

The components of a mixture retain their individual properties.

Question 11

A sample of granite contains visible crystals of quartz, feldspar, and mica. How should granite be classified?

Accepted Answer

Heterogeneous mixture

Question 12

Which of the following best explains why water (H2O) is considered a compound and not a mixture?

Accepted Answer

It has a fixed ratio of hydrogen to oxygen atoms chemically bonded together.

Question 13

Which of the following is an example of a physical change used to separate a mixture?

Accepted Answer

Boiling saltwater to recover salt

Question 14

A hospital uses pure oxygen for patients with respiratory issues. Which classification best fits the oxygen used?

Accepted Answer

Element

Question 15

Which of the following statements about alloys (such as steel or brass) is correct?

Accepted Answer

Alloys are homogeneous mixtures because their composition is uniform throughout.

Question 16

Which of the following best distinguishes a homogeneous mixture from a heterogeneous mixture?

Accepted Answer

Homogeneous mixtures have a uniform composition throughout, while heterogeneous mixtures do not.

Question 17

A student is given a clear, colorless liquid. Which test would best help determine if it is a pure substance or a mixture?

Accepted Answer

Measuring its boiling point and comparing it to known values.

Question 18

Which of the following is a correct comparison between elements and compounds?

Accepted Answer

Elements are made of only one kind of atom, while compounds are made of two or more elements chemically combined.

Question 19

Which of the following best describes the process of separating a mixture of iron filings and sulfur using a magnet?

Accepted Answer

A physical method, because the substances retain their identities.

Question 20

Which of the following is an example of a heterogeneous mixture found in everyday life?

Accepted Answer

Salad

Classification of Matter: Key Definitions and Concepts

Study Guide - Practice Questions