GAT Subject Chemistry MCQs

Mass percent expresses composition on a mass basis.
All component mass percentages sum to 100%.

Mole ratios convert amounts of one substance into another.
They come directly from the balanced equation.

Chemical reactions rearrange atoms but do not create or destroy them.
Therefore total mass remains constant in a closed system.

A pure compound has constant composition.
This is also called the law of constant composition.

Percent composition is calculated from formula mass contributions.
The element percentages sum to approximately 100%.

An empirical formula shows the lowest integer ratio of elements.
It may differ from the molecular formula.

Stoichiometry uses balanced equations to relate amounts.
It supports mass, mole, particle, and gas calculations.

A molecular formula is a whole-number multiple of the empirical formula.
It applies to substances composed of discrete molecules.

Moles equal mass divided by molar mass.
18 g ÷ 18 g/mol = 1 mol.

Solutions are homogeneous mixtures.
Any sampled portion has approximately the same composition.

Heterogeneous mixtures contain distinguishable regions or phases.
Examples include sand in water and granite.

A physical change alters form or state without changing chemical identity.
Ice and liquid water are both H2O.