Which one of the following is an isotonic pair of solutions?

Calculate the amount of solute dissolved in $3 \ dm^3$ water having osmotic pressure $0.3 \ atm$ at $300 \ K$. (Molar mass of solute $= 108 \ g \ mol^{-1}, R = 0.0821 \ atm \ dm^3 \ K^{-1} \ mol^{-1}$) (in $g$)

Calculate the molar mass of solute in a solution prepared by dissolving $1 \ g$ in $0.3 \ dm^3$ solvent having osmotic pressure $0.2 \ atm$ at $300 \ K$. $\left[R=0.082 \ dm^3 \ atm \ K^{-1} \ mol^{-1}\right]$

An aqueous solution of volume $300 \, cm^3$ contains $0.63 \, g$ of protein. The osmotic pressure of the solution at $300 \, K$ is $1.29 \, mbar$. The molar mass of the protein is $......... \, g \, mol^{-1}$. Given : $R = 0.083 \, L \, bar \, K^{-1} \, mol^{-1}$

$A$ solution of polystyrene in benzene contains $10 \, g/L$. The equilibrium height of the column of solution having density $0.9 \, g/mL$ in the osmometer is $11 \, cm$ at $27 \, ^\circ C$. What is the average molar mass of polystyrene? (Assume the solution is ideal)

Which of the following aqueous solutions should have the highest osmotic pressure?