Which of the following shows negative deviation from Raoult's law?

$$5 \mathrm{~g}$$ of non-volatile water soluble compound $$X$$ is dissolved in $$100 \mathrm{~g}$$ of water. The elevation in boiling point is found to be 0.25. The molecular mass of compound $$X$$ is

Abnormal colligative properties are observed only when the dissolved non-volatile solute in a given dilute solution

What would be the van't Hoff factor for a solution prepared by dissolving $$3.42 \mathrm{~g}$$ of $$\mathrm{CaCl}_2$$ in $$2500 \mathrm{~ml}$$ of water having an Osmotic pressure equal to $$0.75 \mathrm{~atm}$$. at $$27^{\circ} \mathrm{C}$$ ? Molar mass of $$\mathrm{CaCl}_2=111 \mathrm{~amu}$$.