A few mixtures are given below. Tabulate the methods to separate their components and give the reasons for selecting the method.

Mixture	Method	Reason
Common salt and ammonium chloride.
Sugar solution
Petrol and Kerosene
Camphor and glass powder
Iron powder and salt

Answer :

Mixture	Method	Reason
Common salt and ammonium chloride.	Sublimation	Ammonium choride changes into vapour directly, but salt does not have this property.
Sugar solution	Evaporation	In sugar solution, sugar is non-volatile.
Petrol and Kerosene	Using separating funnel.	Petrol and kerosene are immiscible.
Camphor and glass powder	Sublimation	Camphor changes into vapour directly.
Iron powder and salt	Using magnet	Iron have a magnetic property.

Given below are certain changes taking place to the particles during change of state. From this, find out and tabulate the changes in the particles when water boils to form steam and also when steam condenses to form water.

Distance increases
Attractive force decreases
Energy increases
Rate of movement increases
Distance decreases
Energy decreases
Attractive force increases
Rate of movement decreases

Answer :

Water boils to form steam	Steam condenses to form water
Distance increases	Distance decreases
Attractive force decreases	Energy decreases
Energy increases	Attractive force increases
Rate of movement increases	Rate of movement decreases

Spirit kept open in a watch glass disappears after some Which among the following phenomena are responsible for this ?

a) Sublimation

b) Distillation

c) Evaporation

d) Diffusion

Answer : Evaporation and diffusion

Which are the methods that can be used to separate the components of a mixture made of common salt, ammonium chloride and sand ?

Write the methods in the order in which they are applied.

Answer :

Heat the mixture of sand, ammonium chloride and salt. Due to “sublimation” ammonium chloride will evaporate.
To the remaining mixture, add some water. Salt is dissolved, from this sand is separated by “filtration”.
Remaining salt can be separated by “distillation”.

Many minerals are present in ordinary water.

a) Which is the method that can be used to remove the minerals and obtain pure water ?

b) In which type of mixtures is this method employed ?

c) Water purified by this method is distilled water. Write two instances of its use ?

Answer :

a) Distillation

b) When one component of the mixture is volatile and the others do not vapourise under the same condition, they can be separated by distillation. If the components of a mixture possess a large difference in their boiling points, they can also be separated by distillation.

c) (1) Used in chemical lab.

(2) Used in storage batteries