Which of the following pairs of solutions can be isotonic at the same temperature?

Solution $A$ contains $7 \ g/L$ of $MgCl_2$ and solution $B$ contains $7 \ g/L$ of $NaCl$. Which of the following is true regarding their osmotic pressure at room temperature?

At a certain temperature,a $1.6 \%$ solution of an unknown substance is isotonic with a $2.4 \%$ solution of Urea. If both solutions have the same solvent and the same density of $1 \ g/cm^3$,what is the molecular mass of the unknown substance in $g/mol$? [Molecular mass of urea $= 60 \ g/mol$]

When the temperature of a certain solution is increased from $37\, ^\circ C$ to $327\, ^\circ C$,how many times will the osmotic pressure change?

The solution containing $4.0 \ g$ of a polyvinyl chloride polymer in $1 \ L$ of dioxane was found to have an osmotic pressure of $6.0 \times 10^{-4} \ atm$ at $300 \ K$. Given $R = 0.082 \ L \ atm \ mol^{-1} \ K^{-1}$,the molecular mass of the polymer is:

The osmotic pressure of solutions of $PVC$ in cyclohexanone at $300 \ K$ are plotted on the graph. The molar mass of $PVC$ is $........ \ g \ mol^{-1}$ (Nearest integer) (Given : $R = 0.083 \ L \ atm \ K^{-1} \ mol^{-1}$ )