48g of Mg contains the same number of atoms as 160g of another element. The atomic mass of the element comes out to be A which is further divided by 20. What is the final answer.

Molar mass of Mg is 24 u and 48 g of Mg has 2 moles of Mg.

$\mathrm{Number} \mathrm{of} \mathrm{atoms}=\frac{48 \mathrm{g}}{24 \mathrm{g}}\times \underset{{\mathrm{N}}_{\mathrm{a}}}{\underbrace{6.022\times {10}^{23}}}\Rightarrow 2{\mathrm{N}}_{\mathrm{a}}$

Element has the same number of atoms and mass is 160 g. Its molar mass is:

$$\begin{gathered} \mathrm{Number} \mathrm{of} \mathrm{atoms}=\frac{\mathrm{given} \mathrm{mass}}{\mathrm{molar} \mathrm{mass}}\times 6.022\times {10}^{23} \\ 2{\mathrm{N}}_{\mathrm{a}}=\frac{160 \mathrm{g}}{\mathrm{molar} \mathrm{mass}}\times {\mathrm{N}}_{\mathrm{a}} \\ \mathrm{molar} \mathrm{mass}=\frac{160 \mathrm{g}}{2}=\underset{\mathrm{A}}{\underbrace{80 \mathrm{g}}} \end{gathered}$$

Final answer when 80 is further divided by 20 is 4.