Which will have minimum osmotic pressure?

Consider the following pairs of solutions which will be isotonic at the same temperature. The number of pairs of solutions that are isotonic is/are..........
$A.$ $1 \ M$ aq. $NaCl$ and $2 \ M$ aq. Urea
$B.$ $1 \ M$ aq. $CaCl_2$ and $1.5 \ M$ aq. $KCl$
$C.$ $1.5 \ M$ aq. $AlCl_3$ and $2 \ M$ aq. $Na_2SO_4$
$D.$ $2.5 \ M$ aq. $KCl$ and $1 \ M$ aq. $Al_2(SO_4)_3$

$0.05 \ M \ CuSO_4$ when treated with $0.01 \ M \ K_2Cr_2O_7$ gives a green coloured solution of $Cu_2Cr_2O_7$. In an osmosis setup with a Semi Permeable Membrane $(SPM)$ separating Side $X$ $(K_2Cr_2O_7)$ and Side $Y$ $(CuSO_4)$,determine the observation due to osmosis.

$A$ solution containing $4 \ g$ of a non-volatile organic solute per $100 \ mL$ has an osmotic pressure of $500 \ cm$ of mercury at $27^\circ C$. What is the molar mass of the solute?

Which of the following colligative properties is most suitable for determining the molar mass of polymers?

If $250 \ cm^3$ of an aqueous solution containing $0.73 \ g$ of a protein $A$ is isotonic with one litre of another aqueous solution containing $1.65 \ g$ of a protein $B,$ at $298 \ K,$ the ratio of the molecular masses of $A$ and $B$ is..........$\times 10^{-2}$ (to the nearest integer).