Which colligative property is most suitable for the determination of the molar mass of polymers?

Which of the following has the highest osmotic pressure at $300 \, K$?

$300 \ mL$ of an aqueous solution of a protein contains $2.52 \ g$ of the protein. If the osmotic pressure of such a solution at $300 \ K$ is $5.04 \times 10^{-3} \ bar$,the molar mass of the protein in $g \ mol^{-1}$ is:

$A$ $5\% \text{ (w/v)}$ solution of cane sugar (molar mass = $342 \text{ g/mol}$) is isotonic with a $1\% \text{ (w/v)}$ solution of an unknown solute. What is the molar mass of the unknown solute in $\text{g/mol}$?

$A$ solution containing $10 \, g \, dm^{-3}$ of urea $(M.wt = 60)$ is isotonic with a $5 \%$ solution of a non-volatile solute. The molecular mass of this non-volatile solute is ......... $g \, mol^{-1}$.

What is a semi-permeable membrane? Give examples.