Question 1

Which of the following best describes a chemical change?

Accepted Answer

A change that results in the formation of a new substance with different properties.

Question 2

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

Accepted Answer

Chicken soup

Question 3

What does the subscript '2' in $$\mathrm{H_2O}$$ indicate?

Accepted Answer

There are two atoms of hydrogen in each molecule of water.

Question 4

Which of the following is NOT a pure substance?

Accepted Answer

Milk

Question 5

A student mixes sand and salt together. Which statement best describes the result?

Accepted Answer

A heterogeneous mixture is formed.

Question 6

Which of the following is a physical change?

Accepted Answer

Boiling water

Question 7

How many atoms are present in one molecule of $$\mathrm{Ca_3$(PO_4$)_2}$$?

Accepted Answer

13

Question 8

Which of the following statements about compounds is correct?

Accepted Answer

Compounds are made of two or more elements chemically combined.

Question 9

Which of the following is a chemical property?

Accepted Answer

Ability to react with acid

Question 10

A sample of matter is uniform throughout and cannot be separated by physical means. Which of the following is it most likely to be?

Accepted Answer

A pure substance

Question 11

Which of the following best describes an element?

Accepted Answer

A substance made of only one kind of atom.

Question 12

Which of the following is NOT a question you must ask to determine if a substance is pure?

Accepted Answer

Is the substance a mixture of two or more phases?

Question 13

Which of the following is a molecule?

Accepted Answer

A group of atoms chemically bonded together

Question 14

What is the main difference between a compound and a mixture?

Accepted Answer

A compound has a fixed ratio of elements, while a mixture does not.

Question 15

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

Accepted Answer

Steel

Question 16

Which of the following best describes the process of a physical change?

Accepted Answer

The substance changes state but retains its chemical identity.

Question 17

Which of the following is a correct statement about atoms?

Accepted Answer

Atoms are the smallest unit that retains the properties of an element.

Question 18

If a molecule contains 2 phosphorus atoms, 3 calcium atoms, and 8 oxygen atoms, which formula represents it?

Accepted Answer

$$\mathrm{Ca_3$(PO_4$)_2}$$

Question 19

Which of the following is a chemical change that occurs in the human body?

Accepted Answer

Digestion of food

Question 20

Which of the following is NOT a characteristic of a mixture?

Accepted Answer

It has a fixed ratio of components.

Introduction to Chemistry: Matter, Substances, and Atoms

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