4.5 g of compound A (MW = 90) was used to make 250 mL of its aqueous solution. The molarity of the solution in M is x $$ \times $$ 10^-1.
The value of x is _______. (Rounded off to the nearest integer)

Consider the following equations :
2Fe²⁺ + H₂O₂ $$ \to $$ xA + yB
(in basic medium)
2MnO₄^- + 6H⁺ + 5H₂O₂ $$ \to $$ x'C + y'D + z'E
(in acidic medium)
The sum of the stoichiometric coefficients x, y, x', y', and z' for products A, B, C, D and E, respectively, is ______.

The mass of ammonia in grams produced when 2.8 kg of dinitrogen quantitatively reacts with 1 kg of dihydrogen is _______.

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)