Page 48 - ICSE Chemistry 6

• In a mixture, original atoms and molecules remain as they are as no chemical change takes place.
• Separa on of components of a mixture some mes becomes essen al because either the mixture
contains undesirable or harmful substances or we need to obtain pure substances from the mixture.
• Some commonly used methods of separa on are sieving, sedimenta on and decanta on, fi ltra on,
evapora on and magne c separa on.
• In sieving, the mixture is passed through a sieve. Fine par cles pass through the sieve while bigger
par cles remain on the sieve.
• Sedimenta on and decanta on is used to separate a heterogeneous mixture of a solid and a liquid
where the solid is heavy and insoluble.
• Filtra on is used to separate an insoluble solid and a liquid by passing the mixture through a fi lter
paper.
• Evapora on is employed to separate a soluble solid component from a liquid.
• Magne c separa on is used when one of the components of a mixture is a magne c substance, i.e.,
it can be a racted by a magnet.

EXERCISES

BE PROMPT

A. Fill in the blanks.
1. An element is a ________________ as it has atoms of only one kind.

2. A symbol represents one _________ of an element.
3. A _________ always contains the same elements combined together chemically in a fi xed ra o.
4. _________ is either absorbed or given out when a compound is formed.

5. The elements present in ammonia are ____________ and ____________.
6. ____________ is used in the prepara on of glass.
7. A sieve consists of a _____________ placed over a frame.
8. The technique of _____________ is used daily in our houses to separate tea leaves from tea using a
_____________.

B. State whether the following statements are true (T) or false (F).
1. An element consists of atoms of diff erent kinds.
2. A compound is pure and homogeneous.

3. A symbol represents one atom of an element.
4. The smallest par cle of a compound is a molecule.
5. Wood produces heat energy on burning and is used as a fuel.
6. A mixture has uniform and constant composi on throughout the whole sample.
7. The cons tuents of a mixture are not chemically combined together.
8. The size of component par cles is not an important factor in the separa on of mixtures.
9. Sedimenta on and decanta on are used to separate a homogeneous mixture of a solid and a liquid.
10. Evapora on is employed to separate a soluble solid component from a liquid.

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