A and B decompose via first order kinetics with half-lives 54.0 min and 18.0 min respectively. Starting from an equimolar non reactive mixture of A and B, the time taken for the concentration of A to become 16 times that of B is _________ min. (Round off to the Nearest Integer).

In Duma's method of estimation of nitrogen, 0.1840 g of an organic compound gave 30 mL of nitrogen collected at 287 K and 758 mm of Hg pressure. The percentage composition of nitrogen in the compound is __________. (Round off to the Nearest Integer). [Given : Aqueous tension at 287 K = 14 mm of Hg]

When 35 mL of 0.15 M lead nitrate solution is mixed with 20 mL of 0.12 M chromic sulphate solution, _________ $$\times$$ 10^$$-$$5 moles of lead sulphate precipitate out. (Round off to the Nearest Integer).

Sulphurous acid (H₂SO₃) has Ka₁ = 1.7 $$\times$$ 10^$$-$$2 and Ka₂ = 6.4 $$\times$$ 10^$$-$$8. The pH of 0.588 M H₂SO₃ is __________. (Round off to the Nearest Integer).