Question

give reason for the following

1) salt and sand cannot be separated by winnowing - ?

2) oil and water can be easily separated by decantation - ?
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Answer 1

Answer:

salt and sand have very fine particles and are of almost same mass and size

due to difference in density of water and oil

Answer 2

1. We can't separate the mixture of powdered salt and sugar by the winnowing method because it separates heavier and lighter components of a mixture while it becomes a homogeneous solution.
2. When a mixture of the two liquids is allowed to settle, the oil will float on top of the water so the two components may be separated.