Question

$4.6\times {10}^{22}$ atoms of an element weight $13.8$ g. What is the atomic mass of the element?

• A. 290 u
• B. 180.6 u
• C. 34.4 u
• D. 104 u

Answer 1

The correct option is B 180.6 u

$1$ mole of any substance contains $6.02\times {10}^{23}$ atoms.
Thus, $4.6\times {10}^{22}$ atoms corresponds to $\frac{4.6\times {10}^{22}}{6.022\times {10}^{23}}=0.0764$ moles.

$0.0764$ moles weighs $13.8$ g.

Thus, $1$ mole will weigh $\frac{13.8}{0.0764}=180.6g$.

Hence, the atomic mass of the element will be 180.6 u.