Practice Test 12

Two particle-level models show substances made from hydrogen and oxygen.

Substance A: HO (2 H atoms and 1 O atom per molecule)

Substance B: HO (2 H atoms and 2 O atoms per molecule)

Which statement best describes the pattern in atom ratios that makes these different substances?

Two particle models show different forms of oxygen.

Substance A: O (two oxygen atoms per molecule)

Substance B: O (three oxygen atoms per molecule)

What pattern explains why Substance A and Substance B are different substances even though they contain the same element?