Question 1

Which of the following is classified as a pure substance?

Accepted Answer

Aluminum foil

Question 2

Which statement best describes a compound?

Accepted Answer

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

Question 3

Table salt ($$\mathrm{NaCl}) is $$classified as which of the following?

Accepted Answer

Compound

Question 4

Which of the following is a homogeneous mixture?

Accepted Answer

Brass (copper and zinc alloy)

Question 5

A student separates a mixture of sand and salt water by filtration. What type of mixture is being separated?

Accepted Answer

Heterogeneous mixture

Question 6

Which of the following is NOT a pure substance?

Accepted Answer

Air

Question 7

Which of the following best describes the composition of a homogeneous mixture?

Accepted Answer

Its composition is uniform throughout.

Question 8

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

Accepted Answer

Copper metal and water

Question 9

Which process can be used to separate the components of a mixture?

Accepted Answer

Filtration

Question 10

Which of the following statements is true about elements?

Accepted Answer

Elements consist of only one type of atom.

Question 11

A scuba tank contains a mixture of oxygen and helium gases. This mixture is best classified as:

Accepted Answer

Homogeneous mixture

Question 12

Which of the following is a correct chemical formula for a compound?

Accepted Answer

$$\mathrm{H_2O_2}$$

Question 13

When table salt ($$\mathrm{NaCl}) is $$decomposed, which elements are produced?

Accepted Answer

Sodium and chlorine

Question 14

Which of the following is a mixture that can be separated by physical methods?

Accepted Answer

Salt water

Question 15

Which of the following is a property of a compound?

Accepted Answer

It has a fixed, definite composition.

Question 16

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

Accepted Answer

Aluminum ($$\mathrm{Al})$$

Question 17

Which of the following best describes a mixture?

Accepted Answer

A combination of two or more substances physically mixed but not chemically combined

Question 18

Which of the following is a real-world example of a homogeneous mixture used in medicine?

Accepted Answer

A nitrox mixture in a scuba tank

Question 19

Which of the following is NOT a characteristic of a heterogeneous mixture?

Accepted Answer

Its composition is uniform throughout.

Question 20

Which of the following is a multi-step process that demonstrates the difference between a compound and a mixture?

Accepted Answer

Separating sand from water by filtration, then decomposing water ($$\mathrm{H_2O}) $$into hydrogen and oxygen by electrolysis

Classification of Matter: Pure Substances and Mixtures

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