MCQ Collection
USAT Chemistry MCQs
Practice USAT Chemistry questions with answers and explanations.
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Correct Answer: D. A pure substance containing elements chemically combined in fixed proportions
Explanation:
Compounds have definite formulas and characteristic properties.
Their components can be separated only by chemical means.
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Correct Answer: A. A physical combination of substances with variable composition
Explanation:
Mixture components retain much of their individual identity.
They can often be separated by physical methods.
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Correct Answer: B. A mixture with uniform composition throughout
Explanation:
Solutions are homogeneous mixtures.
Any sampled portion has approximately the same composition.
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Correct Answer: C. A mixture with nonuniform composition
Explanation:
Heterogeneous mixtures contain distinguishable regions or phases.
Examples include sand in water and granite.
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Correct Answer: D. Melting of ice
Explanation:
A physical change alters form or state without changing chemical identity.
Ice and liquid water are both H2O.
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Correct Answer: A. Rusting of iron
Explanation:
Rusting forms new iron oxide substances.
Chemical changes involve rearrangement of atoms and new products.
