Explain the need for a reference atom for atomic mass. Give some information about two reference atoms.

What is meant by Unified Atomic Mass?

Explain with examples what is meant by a 'mole' of a substance.

Write the name of the ${\mathrm{Na}}_2{\mathrm{SO}}_4$ compound and deduce its molecular mass.

Write the name of the ${\mathrm{K}}_2{\mathrm{CO}}_3$ compound and deduce its molecular mass.

Write the name of the ${\mathrm{CO}}_2$ compound and deduce its molecular mass.

Write the name of the ${\mathrm{MgCl}}_2$ compound and deduce its molecular mass.

Write the name of the $\mathrm{NaOH}$ compound and deduce its molecular mass.

Write the name of the ${\mathrm{AlPO}}_4$ compound and deduce its molecular mass.