Which among the following salts exhibits inverse relation between it's solubility and temperature?

If $$0.01 \mathrm{~m}$$ aqueous solution of an electrolyte freezes at $$-0.056 \mathrm{~K}$$. Calculate van't Hoff factor for an electrolyte (cryoscopic constant of water $$=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$$ )

Calculate van't Hoff factor of $$\mathrm{K}_2 \mathrm{SO}_4$$ if $$0.1 \mathrm{~m}$$ aqueous solution of $$\mathrm{K}_2 \mathrm{SO}_4$$ freezes at $$-0.43{ }^{\circ} \mathrm{C}$$ and cryoscopic constant of water is $$1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$$.

A solution of $$5.6 \mathrm{~g}$$ non-volatile solute in $$50 \mathrm{~g}$$ solvent has elevation in boiling point $$1.75 \mathrm{~K}$$. What is the molar mass of solute $$\left(\mathrm{K}_{\mathrm{b}}=3 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right)$$ ?