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).

For the reaction $$A(g) \rightleftharpoons B(g)$$ at 495 K, $$\Delta$$_rG$$^\circ$$ = $$-$$9.478 kJ mol^$$-$$1.
If we start the reaction in a closed container at 495 K with 22 millimoles of A, the amount of B in the equilibrium mixture is ____________ millimoles.
(Round off to the Nearest Integer). [R = 8.314 J mol^$$-$$1 K^$$-$$1; ln 10 = 2.303]

$$2MnO_4^ - + b{C_2}O_4^{2 - } + c{H^ + } \to xM{n^{2 + }} + yC{O_2} + z{H_2}O$$

If the above equation is balanced with integer coefficients, the value of c is ___________. (Round off to the Nearest Integer).

A 6.50 molal solution of KOH (aq.) has a density of 1.89 g cm^$$-$$3. The molarity of the solution is ____________ mol dm^$$-$$3. (Round off to the Nearest Integer).

[Atomic masses : K : 39.0 u; O : 16.0 u; H : 1.0 u]