In which case is Raoult's law not applicable?

The correct order of boiling point of the given aqueous solutions is:

The osmotic pressure of a $0.1 \ M$ solution of $NaCl$ and $Na_2SO_4$ will be:

Which of the following aqueous solutions has the highest boiling point,under identical conditions having a concentration of $0.03 \ m$?

Calculate the freezing point (in ${}^{\circ}C$) of a solution obtained by dissolving $0.1 \ g$ of potassium ferricyanide (molecular weight $= 329$) in $100 \ g$ of water. Given that $K_f$ for water is $1.86 \ K \ kg \ mol^{-1}$.

In comparison to a $0.01 \ M$ solution of glucose,the depression in freezing point of a $0.01 \ M \ MgCl_2$ solution is (Molecular weight of $MgCl_2 = 95$,molecular weight of glucose $= 180$).