Question 1

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

Accepted Answer

Dissolving sugar in water

Question 2

Which process is classified as a chemical change?

Accepted Answer

Burning wood

Question 3

A student adds lemon juice to cabbage juice, causing the color to change from purple to deep red. What type of change is this and why?

Accepted Answer

Chemical change, because a new substance is formed

Question 4

Which of the following best describes a reversible change?

Accepted Answer

Melting a chocolate bar and then re-solidifying it in the freezer

Question 5

Which phase change is represented by the following equation? $ \mathrm{CO_2 (s) \rightarrow CO_2 (g)} $

Accepted Answer

Sublimation

Question 6

Which of the following is NOT a physical change?

Accepted Answer

Burning a candle

Question 7

A student mixes milk and vinegar, resulting in the formation of curds. What type of change has occurred?

Accepted Answer

Chemical change, because a new substance (curds) is formed

Question 8

Which of the following best describes the process of freezing?

Accepted Answer

A liquid turning into a solid

Question 9

Which of the following is an example of an irreversible change?

Accepted Answer

Burning gasoline in a car engine

Question 10

Which process involves a chemical reaction?

Accepted Answer

Cooking an egg

Question 11

Which of the following phase changes is correctly matched with its direction?

Accepted Answer

Sublimation: solid to gas

Question 12

A student observes that sugar caramelizes when heated on a skillet. What type of change is this?

Accepted Answer

Chemical change, because new substances are formed

Question 13

Which of the following is a correct example of a reversible physical change?

Accepted Answer

Dissolving salt in water

Question 14

Which of the following best describes the process of condensation?

Accepted Answer

A gas turning into a liquid

Question 15

Which of the following is a chemical change that occurs in everyday life?

Accepted Answer

Milk souring when left out of the refrigerator

Question 16

Which of the following best explains why dissolving sugar in water is considered a physical change?

Accepted Answer

Because the sugar can be recovered by evaporating the water

Question 17

Which of the following is an example of deposition?

Accepted Answer

Water vapor turning into ice without becoming liquid

Question 18

A student heats ammonium chloride ($ \mathrm{NH_4Cl} $) and observes the formation of ammonia gas ($ \mathrm{NH_3} $) and hydrogen chloride gas ($ \mathrm{HCl} $). What type of change is this?

Accepted Answer

Chemical change, because new substances are produced

Question 19

Which of the following is an example of a physical change that is NOT easily reversible?

Accepted Answer

Breaking a glass window

Question 20

Which of the following best describes the process of sublimation?

Accepted Answer

A solid turning directly into a gas

Physical and Chemical Changes: Classification and Examples

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