15 mL of aqueous solution of Fe²⁺ in acidic medium completely reacted with 20 mL of 0.03 M aqueous Cr₂O$$_7^{2 - }$$. The molarity of the Fe²⁺ solution is __________ $$\times$$ 10^-2 M. (Round off to the Nearest Integer).

The mole fraction of a solute in a 100 molal aqueous solution is ___________ $$\times$$ 10^$$-$$2. (Round off to the Nearest Integer).

[Given : Atomic masses : H : 1.0 u, O : 16.0 u ]

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).

Complete combustion of 750 g of an organic compound provides 420 g of CO₂ and 210 g of H₂O. The percentage composition of carbon and hydrogen in organic compound is 15.3 and ___________ respectively. (Round off to the Nearest Integer).