Question

$3.011\times {10}^{22}$ atoms of an element weighs $1.15$ g. The atomic mass of an element is :

• A. $10$
• B. $2.3$
• C. $35.5$
• D. $23$

Answer 1

The correct option is D $23$

$3.011\times {10}^{22}$ atoms $=\frac{3.011\times {10}^{22}}{6.022\times {10}^{23}}$
$=1/20=0.05$ moles atoms
If $0.05$ moles $=1.15$ g
then $1$ mole $=1.15/0.05=23$ g