Question 1

Which of the following best describes a pure substance?

Accepted Answer

A material with a fixed composition that cannot be separated into other substances by physical means.

Question 2

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

Accepted Answer

Air (a mixture of gases such as N$$_2$$, O$$_2$$, and CO$$_2).$$

Question 3

Which statement correctly distinguishes between a homogeneous and a heterogeneous mixture?

Accepted Answer

Homogeneous mixtures have a uniform composition throughout, while heterogeneous mixtures have visibly different parts.

Question 4

Which of the following is a compound?

Accepted Answer

Hydrogen peroxide ($$\mathrm{H_2O_2})$$

Question 5

A student mixes table salt ($$\mathrm{NaCl}) $$into water until it dissolves completely. What type of mixture is formed?

Accepted Answer

A homogeneous mixture (solution)

Question 6

Which of the following best explains why methane gas ($$\mathrm{CH_4}) is $$considered a pure substance?

Accepted Answer

It has a fixed composition and cannot be separated into other substances by physical means.

Question 7

Which of the following is NOT a pure substance?

Accepted Answer

Gatorade

Question 8

Which of the following best describes a compound?

Accepted Answer

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

Question 9

A sample of orange juice with pulp is best classified as:

Accepted Answer

A heterogeneous mixture

Question 10

Which of the following statements about mixtures is correct?

Accepted Answer

Mixtures can be separated into their components by physical means.

Question 11

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

Accepted Answer

Orange juice with pulp

Question 12

Which of the following best describes the term 'uniform composition' as it applies to chemistry?

Accepted Answer

The composition is the same throughout the sample.

Question 13

Which of the following substances is an element?

Accepted Answer

Graphite

Question 14

A mixture of sand and iron filings is best separated by which method?

Accepted Answer

Using a magnet

Question 15

Which of the following is a property of a homogeneous mixture?

Accepted Answer

Its composition is uniform throughout.

Question 16

Which of the following is a correct classification for aluminum foil?

Accepted Answer

Element

Question 17

Which of the following is a correct classification for vinegar (an aqueous solution of acetic acid)?

Accepted Answer

Homogeneous mixture

Question 18

Which of the following is a correct classification for sodium hydroxide ($$\mathrm{NaOH}$$)?

Accepted Answer

Compound

Question 19

Which of the following is a correct classification for raisin bran cereal?

Accepted Answer

Heterogeneous mixture

Question 20

Which of the following substances from the list is a pure substance?

Accepted Answer

Table salt ($$\mathrm{NaCl})$$

Classification of Matter: Pure Substances and Mixtures

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