Calculate the molarity of a solution prepared by dissolving $7.1 \ g$ of sodium sulfate $(Na_2SO_4)$ in water to make $100 \ mL$ of solution. (in $M$)

Calculate the mass of urea $[NH_2CONH_2]$ required in making $2.5 \ kg$ of $0.25 \ m$ aqueous solution. (in $g$)

When a solute is present in trace quantities,the following expression is used:

The density of $3 \ M$ solution of $NaCl$ is $1.0 \ g \ mL^{-1}$. Molality of the solution is $...... \times 10^{-2} \ m$. (Nearest integer). Given: Molar mass of $Na$ and $Cl$ is $23$ and $35.5 \ g \ mol^{-1}$ respectively.

Calculate the mass percentage of aspirin $(C_{9}H_{8}O_{4})$ in acetonitrile $(CH_{3}CN)$ when $6.5 \ g$ of $C_{9}H_{8}O_{4}$ is dissolved in $450 \ g$ of $CH_{3}CN$.

In a solution of $7.8 \ g$ benzene $(C_6H_6)$ and $46.0 \ g$ toluene $(C_6H_5CH_3)$,the mole fraction of benzene in this solution is: