tolong kak soalnya aku tidak mampu mengerjakan

a) misalkan massa larutan urea = 100 gr
Massa CO(NH2)2 = 10/100 × 100 = 10 gr
Massa air = 100-10 = 90 gr
Mol urea = mu = 10/60 = 1/6 mol
Mol air = ma = 90/18 = 5 mol
Fraksi mol air = Xa = na/(na+nu) = 5/(5+1/6) = 30/31
P larutan = Xa. Po = 30/31 × 6,2 = 6 cmHg

b) ΔTf = massa urea/Mr × 1000/massa air × Kf
= 10/60 × 1000/90 × 1,86
= 3,44
Jd ttk beku larutan = - 3,44°C