Page 65 - ICSE Chemistry 8

C. Answer in short.
1. What is a pure substance? Write the characteris cs of a pure substance.

2. What is a suspension? Give examples.
3. Write the examples of the following types of mixtures.

(a) Solid-liquid mixture

(b) Solid-gas mixture
(c) Liquid-liquid mixture

(d) Gas-gas mixture
4. Why is it essen al to separate mixtures?

5. What is handpicking?
6. What is winnowing?

7. What is the principle of centrifuga on?
8. Why is frac onal dis lla on used?

AT LENGTH

A. Diff eren ate between the following.

1. Pure substances and mixtures

2. Elements and compounds
3. Homogeneous mixtures and heterogeneous mixtures

4. Sieving and magne c separa on
5. Gravita on and solvent extrac on

6. Filtra on and dis lla on

B. Read the following paragraph. Iden fy the incorrect parts.
A separa ng funnel is a device made up of steel with a tap called stopclock. The stopclock is a ached
to the top of the funnel and controls the fl ow of the liquid. The separa ng funnel is used to separate a
mixture of miscible liquids, i.e., an emulsion. The principle behind the separa on of the liquids is that the
heavier liquid fl oats above the lighter liquid.
• The mixture to be separated is put into a beaker and is allowed to se le.
• A er some me, the liquids mix with each other.

• The liquid forming the upper layer is collected on opening the stopclock.

• The stopclock is opened once the liquid is collected in the separa ng funnel.
• The liquid forming the lower layer is collected in another container in the same way.
This method is used to separate a mixture of oil and water.

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