Perhydrol means 30% solution of H2O2. H2O2 decomposes as 2H2O2→2H2O+O2 Volume strength of 30%H2O2 solution is 100 that means 1‌mL of this solution on decomposition gives 100‌mL oxygen. ‌SO2+‌
1
2
O2→SO3 Since, 100‌mL of oxygen is obtained by =1‌mL‌ of ‌H2O2 ∴1000‌mL of oxygen will be obtained by ‌=‌
1
100
×1000‌mL‌ of ‌H2O2 ‌=10‌mL‌ of ‌H2O2