$3.1 \ g$ of a compound,'$X$' (molar mass $= 62 \ g \ mol^{-1}$) is dissolved in $19.5 \ g$ of other compound,$Y$ (molar mass $= 78 \ g \ mol^{-1}$). The ratio of mole fractions of $X$ and $Y$ in the solution is

If the density of some lake water is $1.25\, g\, mL^{-1}$ and contains $92\, g$ of $Na^{+}$ ions per $kg$ of water,calculate the molality of $Na^{+}$ ions in the lake. (in $, m$)

$3.0 \ g$ ethanoic acid in $50 \ g$ benzene has . . . . . . molality. (Atomic weights: $H=1, C=12, O=16$).

Increasing the temperature of an aqueous solution will cause

The molarity of the solution prepared by dissolving $6.3 \ g$ of oxalic acid $(H_{2}C_{2}O_{4} \cdot 2H_{2}O)$ in $250 \ mL$ of water in $mol \ L^{-1}$ is $x \times 10^{-2}$. The value of $x$ is ..... . (Nearest integer)
[Atomic mass : $H: 1.0, C: 12.0, O: 16.0]$

$A$ compound $H_2X$ with molar weight of $80 \ g \ mol^{-1}$ is dissolved in a solvent having density of $0.4 \ g \ mL^{-1}$. Assuming no change in volume upon dissolution,the molality of a $3.2 \ M$ solution is: