If $5.85 \ g$ of $NaCl$ is dissolved in $90 \ g$ of water,then find out the mole fraction of $NaCl$.

$A$ solution of a solute in benzene has a molality of $X \ m$. If the mole fraction of the solute is $0.2$,what is the value of $X$?

The molarity of the solution obtained by mixing $50 \ mL$ of concentrated $H_2SO_4$ $(36 \ N)$ with $50 \ mL$ of water is .......... $M$.

Calculate the molarity of a solution containing $5 \, g$ of $NaOH$ in $450 \, mL$ solution. (in $, M$)

Two solutions of a substance (non-electrolyte) are mixed in the following manner: $480 \ mL$ of $1.5 \ M$ first solution $+ 520 \ mL$ of $1.2 \ M$ second solution. What is the molarity of the final mixture $.......... \ M$.

If $80 \ g$ of copper sulphate $CuSO_{4} \cdot 5H_{2}O$ is dissolved in deionised water to make $5 \ L$ of solution. The concentration of the copper sulphate solution is $x \times 10^{-3} \ mol \ L^{-1}$. The value of $x$ is .... .
[Atomic masses: $Cu = 63.54 \ u, S = 32 \ u, O = 16 \ u, H = 1 \ u$]