P.1.1 Review Questions

This chart represents several compounds and their chemical formulas. Which explains why the same elements can create many different compounds?

• Elements combine in the same way to produce a variety of substances.

• Elements have the ability to change electron size in order to combine with many different elements.

• Elements combine in a multitude of ways to produce compounds that account for all living and nonliving substances.

Answer explanation

Elements combine in the same way to produce a variety of substances.

Why does hydrogen (H) have a different subscript in each substance?

• The subscript indicates the number of hydrogen atoms in each substance.

• The subscript indicates the number of mixtures that the hydrogen is forming.

• The subscript indicates the number of compounds that the hydrogen is forming.

• The subscript indicates whether the hydrogen is forming a compound or a mixture.

Answer explanation

The subscript indicates the number of hydrogen atoms in each substance.

Which two elements make up household ammonia?

• neon and helium

• neon and hydrogen

• nitrogen and helium

• nitrogen and hydrogen

Answer explanation

Household ammonia is composed of nitrogen and hydrogen, making the correct answer choice nitrogen and hydrogen.

Which can best be concluded from the information in the table showing common compounds and their chemical formulas?

• Some compounds contain only one element.

• All compounds contain the same number of elements.

• Elements combine in many ways to form different compounds.

• Elements combine in the same way to form different compounds.

Answer explanation

Elements combine in many ways to form different compounds.

Which is most likely to be a mixture?

• A substance formed when one atom combines with another atom of the same element.

• A substance formed when one atom combines with an atom of another element.

• A solution formed when one substance chemically combines with another.

• A solution formed when one substance dissolves in another.

Answer explanation

The correct choice is a solution formed when one substance dissolves in another, which is a typical characteristic of mixtures.

Water (H₂O) and table salt (NaCl) can be combined to form salt water. How can this combination be classified?

• as a compound because the water (H₂O) and table salt (NaCl) are chemically combined

• as a compound because the water (H₂O) and table salt (NaCl) form a new pure substance

• as a mixture because the water (H₂O) can be evaporated and physically separated from the table salt (NaCl)

Answer explanation

as a mixture because the water (H₂O) can be evaporated and physically separated from the table salt (NaCl)

Iron filings are thrown into a pile of sand. What is the best way to separate this mixture?

• Use a magnet to pick up the sand.

• Sift through the sand for all of the iron.

• Use a magnet to pick up the iron filings.

Answer explanation

Use a magnet to pick up the iron filings.

Match the following states of matter with the condition where atoms are tightly packed together.

• Atoms are loosely packed, moving freely

• solid

• Atoms are close but can flow around each other

• liquid

• Atoms are tightly packed together

• gas

Answer explanation

In the solid state of matter, atoms of an element are tightly packed together, making it the correct choice for this question.

How are atoms combined in a mixture?

• chemically combined and cannot be separated

• physically combined and can be separated

• chemically combined and can be separated

Answer explanation

Atoms in a mixture are physically combined and can be separated through physical means such as filtration or distillation.

Why is carbon an element and not a compound?

• All carbon atoms have the same number of protons.

• Carbon bonds easily with oxygen, but not helium.

• Carbon is found in all living organisms.

Answer explanation

All carbon atoms have the same number of protons, which is a defining characteristic of elements.