Pakistan MCQs

Theoretical yield assumes complete reaction and no losses.
It is calculated from the limiting reactant.

Actual yield is measured after the experiment.
It is usually lower than theoretical yield.

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.

Rusting forms new iron oxide substances.
Chemical changes involve rearrangement of atoms and new products.

Density describes how much mass is packed into a volume.
It is commonly expressed in g/cm³ or kg/m³.

The mole is the SI base unit for amount of substance.
One mole contains Avogadro's number of specified entities.

Avogadro's constant gives the number of entities in one mole.
The entities may be atoms, molecules, ions, or formula units.

Molar mass is numerically related to relative atomic or molecular mass.
Its common unit is g/mol.

Chemistry examines what matter is made of and how it behaves.
It also studies energy changes accompanying chemical processes.

Matter includes solids, liquids, gases, and plasma.
It is composed of atoms, molecules, or ions.