Question 1

Which of the following best describes a chemical reaction?

Accepted Answer

A process in which substances change their composition, producing new substances.

Question 2

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

Accepted Answer

Salt water

Question 3

Which statement about elements is correct?

Accepted Answer

Elements are pure substances that cannot be broken down by chemical means.

Question 4

Which of the following is a compound formula?

Accepted Answer

$$\mathrm{NaCl}$$

Question 5

A student is given a sample of air and a sample of pure helium. Which statement is true?

Accepted Answer

Air is a mixture, while helium is a pure substance.

Question 6

Which of the following is the correct symbol for the element argon?

Accepted Answer

$$\mathrm{Ar}$$

Question 7

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

Accepted Answer

Electrolysis

Question 8

Which of the following is a property of a heterogeneous mixture?

Accepted Answer

The composition varies from one part of the mixture to another.

Question 9

Which of the following is a correct example of a chemical symbol and its element?

Accepted Answer

$$\mathrm{Cu}$$ for copper

Question 10

A student writes the symbol for carbon as $$\mathrm{c}. $$What is wrong with this notation?

Accepted Answer

Element symbols must be written with a capital letter followed by a lowercase letter if needed.

Question 11

Which of the following is a pure substance?

Accepted Answer

Aluminum foil

Question 12

Which of the following best describes matter?

Accepted Answer

Anything that has mass and takes up space.

Question 13

Which of the following is an example of a chemical reaction in daily life?

Accepted Answer

Burning a candle

Question 14

Which of the following is a correct statement about compounds?

Accepted Answer

Compounds contain two or more elements in fixed proportions.

Question 15

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

Accepted Answer

Sugar dissolved in water

Question 16

Which of the following is NOT a chemical?

Accepted Answer

Happiness

Question 17

Which of the following is the smallest unit of matter that can be identified as an element?

Accepted Answer

Atom

Question 18

Which of the following is a correct example of a mixture?

Accepted Answer

Air

Question 19

Which of the following is a correct statement about the periodic table?

Accepted Answer

It lists all known elements.

Question 20

Which of the following is a correct example of a physical method of separation?

Accepted Answer

Distillation of alcohol from water

Chem 1123 Unit 1: Introduction to Chemistry, Matter, and Chemical Calculations

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