What is molecule? and what is the molecular formulae?

molecule is a group of atom. Molecular formula is the presentation of symbols of a molecules in a systematic way.

Explanation:

For eg; O is the 1 atom of oxygen and HCl is the molecules of hydrochroric acid.

Examples of the molecular formula;

hydrogen + chroride = hydrogenchroride

= 2H + 2Cl = 2HCl

A molecular formula consists of the chemical symbols for the constituent elements followed by numeric subscripts describing the number of atoms of each element present in the molecule. The empirical formula represents the simplest whole-integer ratio of atoms in a compound.