Question

Number of oxygen atoms in $8$ g of ozone is :

• A. $6.02\times {10}^{23}$
• B. $\frac{6.02\times {10}^{23}}{2}$
• C. $\frac{6.02\times {10}^{23}}{3}$
• D. $\frac{6.02\times {10}^{23}}{6}$

Answer 1

The correct option is B $\frac{6.02\times {10}^{23}}{2}$

The number of moles is the ratio of mass to molar mass.
Number of moles of ozone = $\frac{8}{46}=\frac{1}{6}$
The number of molecules is the product of the number of moles and the Avogadro's number $N_A$ which is $6.023\times {10}^{23}$.
Number of molecule of $O_3=\frac{1}{6}\times N_A$
1 molecule of ozone contains 3 O atoms.
Hence, the number of O atoms is thrice the number of ozone molecules.
Number of atom of oxygen = $3\times \frac{1}{6}\times N_A=\frac{1}{2}{N}_A=\frac{6.02\times {10}^{23}}{2}$