What is a "semi-permeable membrane"?

$A$ $40 \text{ g}$ non-electrolyte solute having a molar mass of $180 \text{ g mol}^{-1}$ is dissolved in water to form a solution. If the osmotic pressure of the solution is $2 \text{ atm}$ at $300 \text{ K}$, calculate the volume of the solution in $\text{dm}^3$. $(R = 0.0821 \text{ L atm K}^{-1} \text{mol}^{-1})$ (in $\text{ dm}^3$)

$A$ $5\%(w/v)$ solution of sucrose is isotonic with a $1\%(w/v)$ solution of substance '$A$'. What is the molar mass of substance '$A$'?

Which of the following statements associated with an isotonic solution is not correct?

$90 \, g$ of $CH_3COOH$ $(i = 0.5)$ is dissolved in $110 \, g$ of benzene. What will be its osmotic pressure at $300 \, K$ if the density of the solution is $1.2 \, g/mL$? (Answer in $atm$)

Calculate the osmotic pressure of $0.5 \ M$ aqueous solution of a non-volatile solute at $300 \ K$ $\left[R = 0.0821 \ atm \ dm^3 \ K^{-1} \ mol^{-1}\right]$. (in $atm$)