Question

Calculate the number of moles of $H_2$ in a sample containing $3.011\times {10}^3{H}_2$ molecules.

• A. $5\times {10}^{21}$
• B. $5\times {10}^{-21}$
• C. $2\times {10}^{20}$
• D. $2\times {10}^{-20}$

Answer 1

The correct option is B $5\times {10}^{-21}$

$Numberofmoles=\frac{Numberofmolecules}{Avogadronumber}$
$=\frac{3.011\times {10}^{3}molecules}{6.022\times {10}^{23}molecules/mol}$
$=5\times {10}^{-21}moles$