Which of the following is $NOT$ used as a semipermeable membrane?

$A$ solution containing $8.6 \ g$ of urea per liter is isotonic with a $0.5\% \ (w/v)$ solution of a non-volatile organic solute. What is the molar mass of the organic solute?

Which of the following statements regarding isotonic solutions is $NOT$ correct?

At $17^\circ C$,the osmotic pressure of an aqueous solution of sucrose $(C_{12}H_{22}O_{11})$ containing $34.2 \ g/L$ is $P$. What concentration of glucose $(C_6H_{12}O_6)$ in $g/L$ would be isotonic with this solution?

$XY$ is the membrane $/$ partition between two chambers $1$ and $2$ containing sugar solutions of concentration $c_1$ and $c_2$ $(c_1 > c_2)$ $mol \ L^{-1}$. For the reverse osmosis to take place,identify the correct condition (Here $p_1$ and $p_2$ are pressures applied on chamber $1$ and $2$):
$(A)$ Membrane $/$ Partition $:$ Cellophane,$p_1 > \pi$
$(B)$ Membrane $/$ Partition $:$ Porous,$p_2 > \pi$
$(C)$ Membrane $/$ Partition $:$ Parchment paper,$p_1 > \pi$
$(D)$ Membrane $/$ Partition $:$ Cellophane,$p_2 > \pi$
Choose the correct answer from the options given below $:$

$A$ 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)