Page 81 - ACTIVE SCIENCE 4 TOC

Glossary
• Rotation : The movement of the earth around the sun on its own axis.

• Revolution : The movement of the earth around the sun in its own orbit.

• Sedimentation : To separate the insoluble impurities from water is called
sedimentation.
• Decantation : Water is poured into another vessel after sedimentation.

• Filtration : To separate the insoluble impurities from water using filter
paper.
• Chlorination : To add chlorine into water to kill the harmful germs.

Practice Time

A. Tick the correct option.

1. Changes in weather are caused due to ______________.

a. rotation of the sun b. rotation of the earth
c. revolution of the earth d. revolution of the sun

2. The earth takes ______________ to complete one revolution.
a. 366 days b. 365 days

c. 24 hours d. 365 days and 6 hours

3. The wind which blows from sea to land is called ______________.
a. sea breeze b. land breeze

c. air breeze d. sun breeze
4. The process of water changing into water vapour by heat is called ______________.

a. evaporation b. sedimentation
c. decantation d. condensation

B. Fill in the blanks.
1. The portion of the earth which faces the sun has _____________ season.

2. The portion of the earth which faces away from the sun has _____________ season.

3. Moving air is called _____________.
4. We feel _____________ breeze during daytime.

5. The process of separating insoluble impurities from water using filter paper is
called _____________.
6. The process of adding chlorine into water to kill the harmful germs is called
_____________.

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