Midterm genchem review

Which of the following is a heterogeneous mixture?

• Air

• Vinegar

• Brass

• Sand and water

Which of the following best describes an element?

• A substance composed of identical atoms

• A mixture of compounds

• A compound that cannot be separated by physical means

• A substance that can be decomposed chemically

Which separation method would best separate salt dissolved in water?

• Filtration

• Distillation

• Decantation

• Chromatography

The SI base unit for mass is:

• Gram

• Kilogram

• Pound

• Mole

A student measures a known 25.00 mL sample as 24.98, 25.02, and 24.99 mL.

These results are:

• Precise but not accurate

• Accurate but not precise

• Both precise and accurate

• Neither precise nor accurate

Brass is an example of:

• Compound

• Heterogeneous mixture

• Homogeneous mixture

• Element

Which pair represents a mixture?

• Sodium + chlorine

• S + Cl

• Fe + S (no reaction)

• H + O (reaction happens)

Homogeneous mixtures are also called:

• Compounds

• Solutions

• Suspensions

• Alloys

Which of the following is a chemical change?

• Grinding salt

• Dissolving sugar

• Tarnishing silver

• Boiling water

Which process separates a liquid mixture based on boiling points?

• Filtration

• Distillation

• Decantation

• Sublimation