Question 1

A sample of an unknown metal has a mass of 45.0 g and occupies a volume of 5.00 cm³. Which of the following statements is correct regarding the density and classification of this sample?

Accepted Answer

The density is 9.00 g/cm³, and if the sample is pure, it is a pure substance.

Question 2

Which of the following best describes why 14K gold is classified as a mixture, while 24K gold is not?

Accepted Answer

14K gold contains other metals physically mixed with gold, while 24K gold is pure gold.

Question 3

Which of the following is an example of an intensive property?

Accepted Answer

Density

Question 4

A chemist wants to separate a mixture of sand and iron filings. Which separation technique would be most effective and why?

Accepted Answer

Using a magnet, because iron filings are magnetic and sand is not.

Question 5

Which of the following changes is an example of an endothermic process?

Accepted Answer

Ice melting to form liquid water

Question 6

Which statement correctly distinguishes between a compound and a mixture?

Accepted Answer

A compound has a fixed composition and can only be separated by chemical means, while a mixture can be separated by physical means.

Question 7

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

Accepted Answer

Distillation, to see if it separates into components with different boiling points.

Question 8

Which of the following is a correct statement about allotropes?

Accepted Answer

Allotropes are different forms of the same element in the same physical state.

Question 9

How many atoms are present in 0.68 moles of zinc (Zn)? (Avogadro's number = 6.02 × 10²³)

Accepted Answer

4.09 × 10²³ atoms

Question 10

Which of the following best explains why density is considered an intensive property?

Accepted Answer

It does not depend on the amount of substance present.

Question 11

A 16.2 cm³ sample of lead (Pb) has a density of 11.35 g/cm³. What is its mass?

Accepted Answer

184 g

Question 12

Which of the following is a chemical property?

Accepted Answer

Reactivity with water

Question 13

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture with uniform composition throughout, such as air.

Question 14

Which process is used to separate a mixture of two liquids with different boiling points?

Accepted Answer

Distillation

Question 15

Which of the following is a correct statement about the Law of Conservation of Energy?

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 16

Which of the following is an example of a diatomic element?

Accepted Answer

O₂

Question 17

A student has 2.65 × 10²³ atoms of neon (Ne). How many moles of neon does the student have? (Avogadro's number = 6.02 × 10²³)

Accepted Answer

0.440 moles

Question 18

Which of the following best describes the difference between a physical and a chemical change?

Accepted Answer

A physical change does not alter the chemical identity, while a chemical change does.

Question 19

Which of the following is a correct classification for brass?

Accepted Answer

A homogeneous mixture (alloy)

Question 20

Which of the following best describes the process of sublimation?

Accepted Answer

A solid changing directly to a gas

Fundamental Concepts in General Chemistry: Matter, Classification, Properties, and the Mole

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