1. Fill in the blanks with the appropriate term.
(a) The capacity of air to hold moisture depends upon the …………… of the air.
Answer: Temperature
(b) Water does not have a …………… but has definite ………… and ………..
Answer: shape, volume, mass
(c) While freezing, the ………….. of water is lowered.
Answer: density
(d) …………….. soil has pH 7.
Answer: Neutral
2. Why is the said that –
(a) Air is a homogeneous mixture of various gases.
Answer:
- Air is made of oxygen, nitrogen, carbon dioxide, water vapour and dust particles.
- All these are in different proportions. Therefore air is a mixture.
(b) Water is a universal solvent.
Answer:
- Water dissolves more substances than any other liquid. It dissolves solids, other liquids and even gases in it. Therefore, it is called as Universal solvent.
- Water is used as a solvent in factories, laboratories, foodstuffs and in various types of biological processes occurring in the body such as digestion, excretion, etc.
(c) There is no alternative to water for cleaning purposes.
Answer:
Water is a universal solvent. It dissolves more substances than any other liquid so there is no alternative to water for cleaning purposes.
3. What will happen if……
(a) The amount of water vapour in the air increases.
Answer: We feel the dampness or the humidity.
(b) Only one crop is grown repeatedly in the soil.
Answer: The fertility of the soil decreases.
4. With whom should I pair up?
| Group A | Group B |
| (1) Air | (a) Excretion |
| (2) Water | (b) Scattering of light. |
| (3) Soil | (c) Plasticity |
Answer:
| Group A | Group B |
| (1) Air | (b) Scattering of light. |
| (2) Water | (a) Excretion |
| (3) Soil | (c) Plasticity |
5. State whether the following statements are true or false.
a. Sandy soil has low capacity for holding water.
Answer:
True
b. Sea water is a bad conductor of electricity.
Answer:
False. Sea water is a good conductor of electricity
c. The substance in which a solute dissolves is called a solvent.
Answer:
True
d. The pressure exerted by air is called atmospheric pressure.
Answer:
True
6. Explain the picture in your own words.
Answers
- Diagram (a): Water is filled in the crack.
- Diagram (b): Water in the crack turns to ice due to a decrease in temperature. When it turns to ice the volume increases and it expands. Due to expansion, the size of the crack widens more than in diagram (a).
