Answer
See the answer below.
Work Step by Step
a) In 1 kg of solution:
N. of moles of solute $(2/100\times 1000\ g)\div 98.08\ g/mol=0.204\ mol$
Molality: $0.204\ mol\div 0.98\ kg=0.208\ m$
F.p depression: $\Delta T_f=iK_fm\rightarrow i=-0.796^{\circ}C\div(-1.86^{\circ}C/m\times 0.208\ m)=2.05$
b) Since i is closer to 2 than 3, $H_3O^++HSO_4^-$ best represents the solution.
