The ratio between the number of atoms in equal volumes of oxygen and ozone under the same conditions is 

Given that the gases have equal volumes and we know that same moles of 

gas acquires equal volume.

So, moles of oxygen = $1$

Moles of ozone =$1$

Atoms of oxygen in $O_2=2x{N}_A(Avogadro\text{'}snumber)$

Atoms of oxygen in $O_3=3x{N}_A(Avogadro\text{'}snumber)$

So, the required ratio is $2:3$.

Therefore, Option (B) is correct