Activity – 2
Classify 20 objects around you as solids, liquids and gases
Solids : Ice, Aluminium, Silver, Calcium, Gold, Iron, Sodium, chloride, Sugar, Wood.
Liquids : Water, benzene, chloroform, oil, honey, glycerine, hydrochloric acid, alcohol, dettol.
Gases : Steam, Air, Oxygen, Hydrogen, Chlorine, Nitrogen, Ammonia, Helium, Argon.
Test yourself
- Objective Questions
- Write true or false for each statement
(a) The molecules of each substance are identical.
Answer. False
(b) The inter-molecular forces are effective at all distances between the two molecules.
Answer. False
(c) The molecules in a substance arc in random motion.
Answer. Tme
(d) In a gas, the molecules can move anywhere in space. .
Answer. Tme
(e) The liquids are less viscous than the gases.
Answer. False
- Fill in the blanks
(a) All the molecules of a substance are identical.
(b) The inter-molecular spacing is least in solids more in liquids and still more in gases.
(c) The molecular motion in liquid and gas is in zig-zag path.
(d) In a solid, the molecules vibrate to and fro but they remain at their fixed positions.
(e) The inter-molecular forces are the weakest in gases.
(f) A solid exerts pressure downwards on its base.
(g) The gases are least dense.
(h) A solid is most rigid.
- Select the correct alternative
(a) The diameter of a molecule is approximately
-
- 1 cm 2. 10 cm 3. 10-10 m 4. 1 m
(b) The inter-molecular forces are strongest in
-
- solids 2. liquids 3. gases 4. both (i) and (ii)
(c) The molecules
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- in solid, liquid and gas, move freely anywhere.
- in a solid, move freely within its boundary.
- in a liquid, move within its boundary. 4. in a gas, move only within its boundary.
(d) The solids are
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- more dense
- less dense
- least dense
- highly compressible
(e) The inter-molecular forces in liquids are
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- as strong as in solids
- stronger than in solids
- weaker than in solids
- weaker than in gases