Question

lesson :- is matter around us pure
class 9th chemistry

1. How can you change a saturated solution to an unsaturated solution
without adding any more solvent to it?
2. Sucrose (sugar) crystals obtained from sugarcane and beetroot are
mixed together. Will it be a pure substance or a mixture? Give reasons
for the same. [NCERT Exemplar]
3. Two liquids 'A' and 'B' are miscible with each other at room
temperature. Which separation technique will you apply to separate the
mixture of 'A' and 'B' if the difference in their boiling points is 27°C?
4. Why is crystallisation technique considered better than simple
evaporation to purify solids?
5. Sea water can be classified as homogeneous as well as heterogeneous
mixture.' Comment. [NCERT Exemplar]​

Answer 1

Explanation:

1.).A saturated solution can be changed into unsaturated solution (without adding solvent) by heating the solution. For instance when a saturated solution of sugar is heated to a higher temperature, it starts dissolving more sugar.

2).Sucrose (sugar) crystals obtained from sugarcane and beetroot are mixed together. Will it be pure substance or a mixture? ... It is because sugar obtained by different sources like sugarcane and beetroot will have the same composition.

3.)When two liquids are miscible then we can separate them by boiling. This process of separation is known as fractional distillation

4.)Crystallization is the better method of separating the mixture than evaporation. This is because, on evaporation, some of the solid particles in mixture get decomposed leaving behind impurities whereas, in crystallization, pure crystals of solids are obtained

5.)Sea-water' is called homogeneous as it contains dissolved salts in it. It may be called heterogeneous as it contains various insoluble components too as sand, microbes, shells made of calcium carbonate and so many other things.

plzz thanx me