Question 1

Which of the following statements best describes the law of conservation of mass?

Accepted Answer

Mass remains constant during any chemical change.

Question 2

A student mixes sand and salt in a beaker. Which method would best separate these two substances?

Accepted Answer

Filtration

Question 3

Which of the following is a chemical property of potassium (K)?

Accepted Answer

It reacts vigorously with water.

Question 4

Which statement correctly distinguishes between a compound and a mixture?

Accepted Answer

A compound is composed of two or more elements chemically combined, while a mixture contains substances physically combined.

Question 5

Which of the following is an example of a physical change?

Accepted Answer

Water boiling to form steam.

Question 6

A sample of matter is easily compressible and has no definite shape or volume. What is its physical state?

Accepted Answer

Gas

Question 7

Which of the following best describes a hypothesis in the scientific method?

Accepted Answer

A tentative explanation of some regularity of nature.

Question 8

Which of the following is NOT a physical property?

Accepted Answer

Ability to react with oxygen

Question 9

Which statement about energy is correct according to the law of conservation of energy?

Accepted Answer

Energy is neither created nor destroyed.

Question 10

A mixture of oil and water is left to stand. The oil floats on top of the water. What type of mixture is this?

Accepted Answer

Heterogeneous mixture

Question 11

Which process is most suitable for separating a homogeneous mixture of two liquids with different boiling points?

Accepted Answer

Distillation

Question 12

Which of the following is true about elements?

Accepted Answer

Elements contain only one kind of atom.

Question 13

Which of the following is a chemical change?

Accepted Answer

Copper reacting with chlorine to form copper(II) chloride.

Question 14

Which statement about compounds is correct?

Accepted Answer

Compounds are pure substances composed of two or more elements chemically combined.

Question 15

Which of the following best describes kinetic energy?

Accepted Answer

Energy associated with motion.

Question 16

A student observes that the mass of a closed system remains unchanged after a chemical reaction. Which law does this observation support?

Accepted Answer

Law of conservation of mass

Question 17

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

Accepted Answer

Air

Question 18

Which statement about the scientific method is correct?

Accepted Answer

It is a general process for advancing scientific knowledge through observation, laws, hypotheses, and theories.

Question 19

According to the law of definite proportions, which statement is true for a pure compound?

Accepted Answer

It always contains the same elements in the same proportions by mass.

Question 20

Which of the following is NOT a method for separating mixtures?

Accepted Answer

Electrolysis

Introduction to Matter and the Scientific Method

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