Question

A dry mixture of kno3 and sand could be separated by

1. adding water to the mixture and filtering
2. adding water to the mixture and evaporating
3. heating the mixture to a high temperature
4. cooling the mixture to a low temperature

Answer 1

Use a little common sense here. KNO3 is soluble in water, sand isn't.

Answer 2

1. KNO3 is soluble in water, whilst sand isn't. Therefore, they will separate when placed in water.