Pakistan MCQs

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

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.

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

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

Balancing follows conservation of atoms and mass.
Coefficients change amounts, not chemical formulas.

Equation coefficients give stoichiometric ratios.
They may be interpreted as molecule or mole ratios.

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

A body in rotational equilibrium has no angular acceleration.
Clockwise and counterclockwise torques balance.

Work is W=Fd when force and displacement are parallel.
W=20×5 = 100 J.