Question

q1.5 which of the following is a pure substance?
a salt water
b air
c carbon dioxide
d salad dressing

q1.6 which pair represents two diatomic elements?
a \\(\text{na}\\) and \\(\text{mg}\\)
b \\(\text{o}_2\\) and \\(\text{cl}_2\\)
c \\(\text{co}_2\\) and \\(\text{h}_2\text{o}\\)
d \\(\text{al}\\) and \\(\text{fe}\\)

q1.7 a mixture that has a uniform appearance throughout is called a _____
a compound
b heterogeneous mixture
c homogeneous mixture
d element

q1.8 in a solution, the substance being dissolved is the _____
a solvent
b suspension
c solute
d precipitate

Explanation:

Identify pure substances

A pure substance has a constant chemical composition. Carbon dioxide is a compound with a fixed chemical formula (\(\text{CO}_2\)), whereas salt water, air, and salad dressing are mixtures.

Identify diatomic elements

Diatomic elements exist naturally as molecules containing two atoms bonded together. Oxygen (\(\text{O}_2\)) and chlorine (\(\text{Cl}_2\)) are both diatomic elements.

Define uniform mixtures

A mixture with a uniform, consistent appearance and composition throughout is classified as a homogeneous mixture.

Define solution components

In a solution, the solute is the substance that is dissolved, while the solvent is the substance doing the dissolving.

Answer:

Question 1.5

• A Salt water
• B Air
• C Carbon dioxide (Correct answer)
• D Salad dressing

Question 1.6

• A Na and Mg
• B \(\text{O}_2\) and \(\text{Cl}_2\) (Correct answer)
• C \(\text{CO}_2\) and \(\text{H}_2\text{O}\)
• D Al and Fe

Question 1.7

• A compound
• B heterogeneous mixture
• C homogeneous mixture (Correct answer)
• D element

Question 1.8

• A solvent
• B suspension
• C solute (Correct answer)
• D precipitate