(b) Maximum 25 g of salt dissolves in 100 g water, after that sedimentation start. Amount of salt in given solution = 1000 x
4
100
= 40 g ∴ Minimum amount of water required after which 40 sedimentation starts = 40/25$$ x 100 = 160g ∴ Minimum 840 g needs to evaporated. Time required to evaporated 840 g of water =
840
28
= 30h ∴ After 31 h, the given solution starts sedimenting.