Question

Calculate the number of molecules of sulphur $\left(S_8\right)$ present in $16\text{g}$ of solid sulphur.
(Given, Atomic mass of sulphur $=32\text{u}$ and $N_A=6.022\times {10}^{23}$)

• A. $4.022\times {10}^{15}\text{molecules}$
• B. $6.022\times {10}^{22}\text{molecules}$
• C. $3.76\times {10}^{22}\text{molecules}$
• D. $3.76\times {10}^{30}\text{molecules}$

Answer 1

The correct option is C $3.76\times {10}^{22}\text{molecules}$

We know,
$\text{Moles}=\frac{\text{Given mass}}{\text{Molar mass}}$
$\text{Moles of}{S}_8=\frac{16}{256}=\frac{1}{16}\text{mol}$
Number of molecules in one mole $=6.022\times {10}^{23}$
Number of molecules in $\frac{1}{16}\text{mol}=\frac{6.022\times {10}^{23}}{16}=3.76\times {10}^{22}\text{molecules}$