Question

Find the number of moles of $N_2{O}_5$ in a pure sample that contains 1 nanomole of O-atoms.

• A. $2\times {10}^{-10}$ moles
• B. $0.2\times {10}^{-10}$ moles
• C. $4\times {10}^{-10}$ moles
• D. $0.4\times {10}^{-10}$ moles

Answer 1

The correct option is A $2\times {10}^{-10}$ moles

5 moles of O-atoms are present in 1 mole of $N_2{O}_5$.
So, 1 nanomole of O-atoms will be present in
$=\frac{1}{5}\times {10}^{-9}$ moles of $N_2{O}_5$
$=2\times {10}^{-10}$ moles of $N_2{O}_5$