need fast. .........

K₄Fe(CN)₆ → 4K⁺ + Fe(CN)₆⁴⁻
i = n = 5

∆Kf = m×Kf×i
∆Kf = (mass/mr × 1000/p)×Kf×i
0,062 = (mass/368 × 1000/500)×1,86×5
mass = 0,062×184/1,86×5
mass = 1,23 gram