A 20.0 mL solution containing 0.2 g impure H₂O₂ reacts completely with 0.316 g of KMnO₄ in acid solution. The purity of H₂O₂ (in %) is _____________
(mol. wt. of H₂O₂ = 34; mol. wt. of KMnO₄ = 158)

The volume (in mL) of 0.1 N NaOH required to neutralise 10 mL of 0.1 N phosphinic acid is ___________.

6.023 $$ \times $$ 10²² molecules are present in 10 g of a substance 'x'. The molarity of a solution containing 5 g of substance 'x' in 2 L solution is _____ × 10^-3

The volume strength of 8.9 M H₂O₂ solution calculated at 273 K and 1 atm is ______. (R = 0.0821 L atm K^-1 mol^-1) (rounded off ot the nearest integer)