Question 1

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

Accepted Answer

Brass (an alloy of copper and zinc)

Question 2

Which statement correctly distinguishes between a compound and a mixture?

Accepted Answer

A compound contains two or more elements chemically combined in a fixed ratio, while a mixture contains substances physically combined in variable proportions.

Question 3

Which of the following is a pure substance?

Accepted Answer

Aluminum foil

Question 4

A sample of hydrogen peroxide, $$\mathrm{H_2O_2}$$, is best classified as:

Accepted Answer

A compound

Question 5

Which method would best separate a mixture of sand and salt?

Accepted Answer

Dissolve the mixture in water, filter to remove sand, then evaporate the water to recover salt.

Question 6

Which of the following is a heterogeneous mixture?

Accepted Answer

A hot fudge sundae

Question 7

Which of the following statements about elements is correct?

Accepted Answer

Elements are pure substances that contain only one type of atom.

Question 8

A scuba tank is filled with a mixture of oxygen and helium gases. This mixture is best described as:

Accepted Answer

A homogeneous mixture

Question 9

Which of the following best describes the composition of a compound?

Accepted Answer

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

Question 10

Which of the following is NOT a physical method for separating mixtures?

Accepted Answer

Electrolysis

Question 11

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

Accepted Answer

Try to separate it by distillation and observe if more than one component is collected.

Question 12

Which of the following is an example of a compound being separated into its elements?

Accepted Answer

Decomposition of sodium chloride, $$\mathrm{NaCl}$$, into sodium and chlorine.

Question 13

Which of the following best describes the difference between a homogeneous and a heterogeneous mixture?

Accepted Answer

A homogeneous mixture has a uniform composition throughout, while a heterogeneous mixture does not.

Question 14

Which of the following is a correct classification for water, $$\mathrm{H_2O}$$?

Accepted Answer

Compound

Question 15

A mixture of copper metal and water is best classified as:

Accepted Answer

A heterogeneous mixture

Question 16

Which of the following is a real-life example of a physical separation method?

Accepted Answer

Using a strainer to separate pasta from water

Question 17

Which of the following is a correct statement about mixtures?

Accepted Answer

Mixtures can be separated into their components by physical methods.

Question 18

Which of the following best describes the composition of air?

Accepted Answer

A homogeneous mixture of gases

Question 19

Which of the following is an example of a pure substance that is an element?

Accepted Answer

Copper, $$\mathrm{Cu}$$

Question 20

A solution of sugar dissolved in water is best classified as:

Accepted Answer

A homogeneous mixture

Chapter 3: Matter and Energy – Classification of Matter

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