∵ 12 g of carbon contains = 6.023 × 10²³ atoms
∴ 3g of carbon will  contain 
 $\frac{6.023\times {10}^{23}}{12}\times 3=\frac{6.023\times {10}^{23}}{4}\text{ atoms }$ 
    Now, 
 6.023 × 10²³ atoms of sulphur has mass = 32g 
$\frac{6.023\times {10}^{23}}{4}$ atoms of sulphur have mass. 
$=\frac{32}{6.023\times {10}^{23}}\times \frac{6.023\times {10}^{23}}{4}=8\mathrm{g}$