Question

if the density of water is 1 g cm^-3, then the volume occupied by one molecule of water is approximately

Answer 1

The density of water is
1gm/cm^3

and molecular mass of one molecule of water is 18gm/mol

it means 1mol of water has 18gm of mass
that is
6.023 *10^23 molecules has 18gm of mass

so 1 molecule had 18/6.023*10^23 gm
so mass of one molecule will be

2.988 * 10^-23 gm
or 3 *10^-23 gm. (approximate)

since
density = mass /volume
so volume = mass /density

so
volume of one molecule of water is

3*10^-23/1
= 3*10^-23cm^3

hope u get this.