Question

1000 g impure sample of NaOH contains 3 mol of oxygen atoms. The $\%$ purity of the sample is:

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Moles of NaOH = moles of oxygen atoms
Mass of NaOH = $3\times 40=120g$
$\therefore$ $\%$ $\text{purity}=\frac{\text{mass of NaOH}}{\text{mass of impure sample}}\times 100=12\%$