Page 83 - Active Science 5 Ebook and Activity

• Decantation : Collection of pure water in a separate container.
• Chlorination : Addition of chlorine to water to kill the germs.

Practice Time

A. Choose the correct option.

1. What is air?
a. A thick covering that surrounds the earth.
b. An empty space in a bottle or tumbler.

c. Mixture of various gases
d. The oxygen we breathe in.

2. A gas that does not burn and helps put out fire is ______________.
a. carbon dioxide b. sulphur dioxide

c. oxygen d. nitrogen
3. The air we breathe out is rich in ______________.

a. nitrogen b. carbon dioxide
c. water vapour d. oxygen
4. Which among the following processes is used for killing germs present in water?

a. Boiling b. Decantation
c. Evaporation d. Condensation

5. Muddy water can be easily cleaned by ______________.
a. distillation b. decantation
c. boiling d. sedimentation and decantation

B. Fill in the blanks.
1. Air is one of the ______________ things that makes life on earth possible.
2. _____________ is the most important for combustion.
3. Air contains ______________ percent oxygen.

4. ______________ is the process which involves boiling followed by condensation.
5. ______________ and sedimentation are two methods to purify water.
6. ______________ is a soluble impurity.

C. Match the following.

1. Oxygen a. helps in burning
2. Carbon dioxide b. occupies space

3. Nitrogen c. is a harmful gas
4. Water e. process to separate soluble substances
5. Distillation f. is a main constituent of blood

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