Define and explain the concept of Molecular Mass.

(N/A) Molecular mass is defined as the sum of the atomic masses of all the elements present in a molecule.
It is calculated by multiplying the atomic mass of each constituent element by the number of its atoms in the molecule and then adding these values together.
For example,the molecular mass of methane $(CH_{4})$,which contains one carbon atom and four hydrogen atoms,is calculated as follows:
Molecular mass of $(CH_{4}) = (12.011 \ u) + 4 \times (1.008 \ u) = 16.043 \ u$.
Similarly,the molecular mass of water $(H_{2}O)$ is calculated as:
Molecular mass of $(H_{2}O) = (2 \times \text{atomic mass of hydrogen}) + (1 \times \text{atomic mass of oxygen}) = (2 \times 1.008 \ u) + 16.00 \ u = 18.02 \ u$.