30 lit of oxygen is liberated at STP by the complete decomposition of a sample of 1 lit of H₂O₂. The molarity of that H₂O₂ solution is nearly

1 lit of H₂O₂ solution 

30lit of "O₂"

i.e.. The volume strength of the H₂O₂ solution is 30vol strength.
 

(OR)
2H₂O₂ → 2H₂O + O₂
2 x 34gr ------22.4 lit
??        -------30lit

M = 2.678M