Reactions involved may be given as:
2KI+H2O+O3→2KOH+I2+O2↑
I2+2Na2S2O3→2NaI+Na2S4O6
1 mole O3=2 mole Na2S2O3....(i)
No. of moles of hypo =MassMolecular mass(158)
=E×N×V1000×158
where, ENa2S2O3=158,N=0.08,V=15
∴ No. of moles of hypo =158×0.08×151000×158=1.2×10−3
No. of moles of O3=12 mole of hypo [from eq. (i)]
=12×1.2×10−3
=6×10−4 mole
Volume of O3 at NTP= No. of moles ×22400
=6×10−4×22400
=13.44 mL at NTP.