Given,
200ml 10Vol. of H2O2 & 50ml 20Vol. of H2O2
The reaction involved is:
2H2O2⟶2H2O+O2
∴10Vol. H2O2 means
1L of H2O2 would produce 10L of O2
⇒10V 200ml of H2O2 would produce
200×101000=2L of O2
Again 20Vol. H2O2 means
1L[1000ml] of H2O2 would produce 20L O2
⇒ 20 Vol. 50ml of H2O2 would produce
50×201000=1L of O2
Thus total volume of oxygen in resulting solution
=2+1=3L=3000ml
Also, Total volume of the solution=200ml+50ml=250ml
⇒250ml of resulting solution produces 3000ml of O2
So, 1000ml of resulting solution would produce
1000250×3000=12000ml of O2 or 12L of O2
∴ Strength of final solution=12 volume H2O2