Which of the following salt solutions is highly acidic?

Molal depression constant for a liquid is $$2.77^{\circ} \mathrm{C} ~\mathrm{kg} ~\mathrm{mol}^{-1}$$, in Kelvin scale it's value is

Which among the following statement is NOT true about homologous series of organic compounds?

If 6 g of solute dissolved in 100 g of water lowers the freezing point by 0.93 K. What is molar mass of solute? (K$$_\mathrm{f}$$ = 1.86 K kg mol$$^{-1}$$)