Question

Calculate the molecular mass of water.

• A. 18

Answer 1

The correct option is A 18
$\bullet$ The molecular mass of a substance is the total mass of atoms in a molecule. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> It is calculated by adding the atomic masses of all the atoms present in the molecule.
$\bullet$ Water $\left({\text{H}}_2\text{O}\right)$ is made up of two hydrogen (H) and one oxygen (O) atom.
So, the molecular mass of ${\text{H}}_2\text{O}$ = atomic mass of O + (2 $\times$ atomic mass of H) = 16 + (2 $\times$ 1) = 18 u