Calculate the mole fraction of urea in an aqueous solution of $1 \ m$ urea $(NH_2CONH_2)$.

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 : $H: 1.0, C: 12.0, O: 16.0]$

Which of the following values changes with a change in temperature?

Calculate the molarity of $NaOH$ in the solution prepared by dissolving $4 \,g$ of it in enough water to form $250 \,mL$ of the solution. (in $,M$)

$63 \ g$ of a compound (Mol. Wt. $= 126$) was dissolved in $500 \ g$ of distilled water. The density of the resultant solution is $1.126 \ g / mL$. The molarity of the solution is: (in $M$)

If $4 \ g$ of $NaOH$ dissolves in $36 \ g$ of $H_2O$,calculate the mole fraction of each component in the solution. Also,determine the molarity of the solution (specific gravity of the solution is $1 \ g \ mL^{-1}$).