Question

Number of $g$ of oxygen in $32.2gN{a}_{2}S{O}_{4}10H_{2}O$ is:[$Mol.wt=322$ ]

• A. $16.0$
• B. $2.24$
• C. $18.0$
• D. $22.4$

Answer 1

The correct option is D $22.4$

Number of gm of oxygen in 32.2 g $N{a}_{2}S{O}_4.10H_{2}O$ is No. of oxygen atoms in one molecule =4+10=14

Thus moles of oxygen in n moles of compound=14n

Molar mass of $N{a}_{2}S{O}_4.10H_{2}O$=46+32+64+180=322g/mol

Thus

$32.2g=\frac{32.2}{322}=0.1mols$

Thus moles of $O=0.1\times 14=1.4$

So weight is

$16\times 1.4=22.4g$

Hence, the correct option is $D$