A student needs to identify two substances, A and B. Substance A can be broken down by a chemical process. Substance B cannot be broken down by a chemical process. What can be concluded about the substances?

A. Both substances are compounds.
Incorrect. Compounds can be broken down by chemical processes.

B. Both substances are elements.
Incorrect. Elements cannot be broken down into simpler substances. They are made of only one type of atom.

C. Substance A is an element and substance B is a compound.
Correct!

D. Substance A is a compound and substance B is an element.
Incorrect. Try rereading the question. Compounds can be broken down by chemical processes and elements cannot be broken down into simpler substances. They are made of only one type of atom.

Which of the following is best separated by filtration?

A. Sand and water
Correct! Filtration will “catch” the sand and not the water.

B. Sand and iron fillings
Incorrect. The filter would hold the iron filings too- a magnet would separate them.

C. Salt and water
Incorrect. Salt is dissolved, so it would not be “caught” by the filter.

D. Sugar and salt
Incorrect. Sugar and salt look a lot alike and a filter would not separate them.

Which description of matter is describing a pure substance?

A. Can be separated by physical means
Incorrect. Pure substances cannot be separated by physical means.

B. Has a constant chemical composition
Correct! This is a characteristic of a pure substance, good!

C. Heterogeneous throughout substance
Incorrect. Pure substances are homogeneous throughout.

D. All other choices are correct.
Incorrect. Try again.

Which of the following petri dishes contains a substance comparable to an element?

A.
Incorrect. An element contains only one kind of matter. This sample has two kinds of matter.

B.
Incorrect. An element contains only one kind of matter. This sample has two kinds of matter.

C.
Incorrect. An element contains only one kind of matter. This sample has three kinds of matter.

D.
Correct! This sample contains only one kind of matter.

Which of the following is heterogeneous?

A. Colloid
Incorrect. A colloid is uniform throughout - homogeneous.

B. Solution
Incorrect. A solution is uniform throughout - homogeneous.

C. Suspension
Correct! A suspension is not uniform throughout and the solids will settle.

D. Compound
Incorrect. A compound is uniform throughout.

Matter can by classified as —

A. elements or compounds
Incorrect. This is how to classify pure substances.

B. mixtures or pure substances
Correct! This is the first classification of matter.

C. suspensions or solutions
Incorrect. This is a classification of mixtures.

D. homogenous mixtures or heterogeneous mixtures
Incorrect. This is a classification of mixtures.