Question 1

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more elements chemically combined in definite proportions.

Question 2

Which property is considered an extensive property?

Accepted Answer

Mass

Question 3

A student observes that copper metal reacts with nitric acid to form nitrogen dioxide gas and a blue mixture. What type of change is this?

Accepted Answer

Chemical change

Question 4

Which separation technique would be most effective for separating a mixture of sand and salt water?

Accepted Answer

Filtration

Question 5

Which statement about the law of constant composition is correct?

Accepted Answer

A compound always contains the same elements in the same proportion by mass.

Question 6

Which of the following is a physical property?

Accepted Answer

Boiling point

Question 7

A sample of water is heated from $$20\ ^\circ\mathrm{C} to$$ $$80\ ^\circ\mathrm{C}. $$What type of change has occurred?

Accepted Answer

Physical change

Question 8

Which of the following best describes kinetic energy?

Accepted Answer

Energy of motion

Question 9

Which formula correctly expresses the kinetic energy of an object?

Accepted Answer

$$KE = \frac{1}{2}mv^2$

Question 10

A car traveling at $$65\ \mathrm{mph}$$ has more kinetic energy than a car traveling at $$35\ \mathrm{mph}$$ because:

Accepted Answer

Kinetic energy increases with the square of velocity.

Question 11

Which of the following is NOT a pure substance?

Accepted Answer

Air

Question 12

Which statement is true about mixtures?

Accepted Answer

Mixtures can be separated by physical means.

Question 13

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

Accepted Answer

Density

Question 14

Which process is used to separate a liquid mixture based on differences in boiling points?

Accepted Answer

Distillation

Question 15

Which statement best explains why the properties of a compound are different from those of its constituent elements?

Accepted Answer

Chemical bonding changes the identity and properties of the elements.

Question 16

Which of the following is a chemical change?

Accepted Answer

Burning of gasoline

Question 17

A mixture of iron filings and sulfur can be separated by:

Accepted Answer

Using a magnet

Question 18

Which of the following is a correct statement about elements?

Accepted Answer

Elements cannot be decomposed into simpler substances by chemical means.

Question 19

Which of the following is a homogeneous mixture?

Accepted Answer

Salt water

Question 20

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

Accepted Answer

Physical changes do not alter the chemical composition of a substance, while chemical changes do.

Introduction to Chemistry: Matter, Properties, and Energy

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