The number of atoms of hydrogen present in 1.5 mole of ${\mathrm{H}}_2\mathrm{O}$ is

1mole${\mathrm{H}}_2\mathrm{O}$=2 mole H atoms

$\frac{2 \mathrm{mol} \text{'}\mathrm{H}\text{'} \mathrm{atoms}}{1 \mathrm{mol} {\mathrm{H}}_2\mathrm{O}}\times 1.5 mol H_{2}O=3 mol H atoms$

Number of ‘H atoms’ present in 1.5 mol of ${\mathrm{H}}_2\mathrm{O}$ is 3N.

Here, N represents Avogadro number.