The mole fraction of urea in an aqueous urea solution containing 900 g of water is 0.05. If the density of the solution is 1.2 g cm^$$-$$3, then molarity of urea solution is ................

(Given data : Molar masses of urea and water are 60 g mol^$$-$$1 and 18 g mol^$$-$$1, respectively)

The amount of water produced (in g) in the oxidation of 1 mole of rhombic sulphur by conc. HNO₃ to a compound with the highest oxidation state of sulphur is ..............

(Given data : Molar mass of water = 18 g mol^$$-$$1)

To measure the quantity of $$MnC{l_2}$$ dissolved in an aqueous solution, it was completely converted to $$KMn{O_4}$$ using the reaction,

$$MnC{l_2} + {K_2}{S_2}{O_8} + {H_2}O \to KMn{O_4} + {H_2}S{O_4} + HCl$$ (equation not balanced).

Few drops of concentrated $$HCl$$ were added to this solution and gently warmed. Further, oxalic acid ($$225$$ $$mg$$) was added in portions till the colour of the permanganate ion disappeared. The quantity of $$MnC{l_2}$$ (in mg) present in the initial solution is ____________.

(Atomic weights in $$g\,\,mo{l^{ - 1}}:Mn = 55,Cl = 35.5$$ )

A compound H₂X with molar weight of 80g is dissolved in a solvent having density of 0.4 gml^–1 . Assuming no change in volume upon dissolution, the molality of a 3.2 molar solution is