If a $0.75\text{g}$ sample contains $3.011\times {10}^{22}$ molecules, what will be the molar mass of the molecule?

The correct option is C $15\text{g/mol}$
Given:
The mass of $3.011\times {10}^{22}\text{molecules}=0.75\text{g}$

So, the mass of $6.022\times {10}^{23}$ molecules = $\frac{6.022\times {10}^{23}\times 0.75}{3.011\times {10}^{22}}\text{g}$
$=15\text{g}$

So, the molar mass of the molecule is $15\text{g/mol}$