Define molecular formula.

Hint: Atom is the smallest particle of an element that may or may not exist independently and retains all its chemical properties. The symbols of some elements are represented by one letter or two letters. Molecules are the combination of two or more elements that are held together by attractive forces. Molecules can be expressed in the form of a chemical symbol.
Complete step by step answer:
Molecular formula is the actual number of atoms of each element in a compound. It also indicates the kinds of atoms. It is generally derived from the Assays and empirical formula by calculations. Molecular formula can be obtained by multiplying the empirical formula with a whole number coefficient. The whole number coefficient is different for different compounds.
If the whole number coefficient is one, which means for some compounds, the molecular formula and empirical formula will be the same.
Molecular formula has numeric subscripts which is the number of atoms. The molecular formula is the same as or multiple of the empirical formula of the molecule. They are easy to communicate. It is different from the structural formula. Structural formula gives information about the bonding and the arrangement of atoms.

Note:Molecular formulas can be written by knowing the symbols of the constituent elements and the combining capacity of each atom constituting the compound. The combining power of an atom is called valency. The number of atoms of other elements with which one atom of an element combines is decided by the valency of that element.