Question 1

Which of the following best describes why table salt ($$NaCl) is $$classified as a compound and not a mixture?

Accepted Answer

Because it consists of two elements chemically bonded together with properties different from the original elements.

Question 2

A student mixes sand and iron filings together. Which classification best fits this combination, and why?

Accepted Answer

Heterogeneous mixture, because the different substances remain visible and can be separated physically.

Question 3

Which of the following is NOT considered matter?

Accepted Answer

Sound

Question 4

Which of the following statements about elements is correct?

Accepted Answer

Elements are pure substances made of only one type of atom.

Question 5

A sample of brass is analyzed and found to contain only copper and zinc, evenly mixed at the atomic level. Which classification best describes brass?

Accepted Answer

Homogeneous mixture (solution)

Question 6

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

Accepted Answer

Salt water

Question 7

Why does sodium chloride ($$NaCl) $$have properties different from both sodium and chlorine?

Accepted Answer

Because the elements are chemically bonded, forming a compound with new properties.

Question 8

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

Accepted Answer

Air

Question 9

A student observes that a liquid sample is uniform throughout and cannot be separated by filtration. Which classification best fits this sample?

Accepted Answer

Homogeneous mixture (solution)

Question 10

Which of the following is the best example of a compound?

Accepted Answer

Water ($$H_2O)$$

Question 11

Which of the following is a correct statement about mixtures?

Accepted Answer

Mixtures retain the properties of their components.

Question 12

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

Accepted Answer

Filtration followed by evaporation

Question 13

Which of the following is true about compounds?

Accepted Answer

They are pure substances that can be broken down by chemical means.

Question 14

Which of the following is NOT a pure substance?

Accepted Answer

Coffee

Question 15

A student claims that air is not a solution because it is a gas. What is the best response?

Accepted Answer

Air is a solution because it is a homogeneous mixture of gases.

Question 16

Which of the following best describes why oil and water form a heterogeneous mixture?

Accepted Answer

Because oil and water do not mix uniformly and remain as separate phases.

Question 17

Which of the following is the best method to separate a homogeneous mixture of two liquids with different boiling points?

Accepted Answer

Distillation

Question 18

Which of the following is a property of pure substances but NOT of mixtures?

Accepted Answer

Have constant, definite physical and chemical properties

Question 19

A sample is uniform throughout, cannot be separated by physical means, and can be broken down into simpler substances by chemical means. What is it?

Accepted Answer

Compound

Question 20

Which of the following best explains why chocolate chip cookies are classified as a heterogeneous mixture?

Accepted Answer

Because the different components can be seen and separated physically.

Classification of Matter: Pure Substances and Mixtures

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