ICSE Chemistry – 6
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Question 1.
Fill in the blanks:

(a) Water is a matter because it has mass and occupies space.
(b) Any matter which has a definite volume but no definite shape is called a liquid.
(c) Liquids and gases can flow.
(d) The molecules are at a greater distance in gases compared to liquids.
(e) Water boils at 100 °C.
(f) The physical state of a substance, which has neither fixed volume nor fixed shape is a gas.

Question 2.
Write whether the following statements are true or false.
(a) Only water can exist in three different states. True
(b) If the container in which a gas is collected has an opening, the gas will flow out and spread itself indefinitely. True
(c) Solids have the large inter-molecular space. False
(d) There is no difference between evaporation and boiling. False
(e) All solids, on heating, first change to the liquid and then to the gaseous state always. False
(f) The intermolecular force of attraction is the weakest in gases. False
(g) A gas has no free surface. True
(h) Solids are highly compressible and rigid. True.
(i) Atoms/molecules in gases move only about their own positions. False.
(j) The conversion of water to ice is called freezing. True.

Question 3.
For each of the following statements, say whether it describes a solid, a liquid or a gas.

(a) Particles move about very quickly but do not leave the surface : Liquid
(b) Particles are quite close together : Solid
(c) Particles are far apart and move in all directions : Gas

Question 4.
Match the following :

Question 5.
Name the phenomenon which causes the following changes:
(a) Formation of water vapor from water.
Answer: Formation of water vapour from water is vaporisation.

(b) Disappearance of camphor when exposed to air.
Answer: Disappearance of camphor is sublimation.

(c) Conversion of ice into water.
Answer: Conversion of ice into water is melting.

(d) Conversion of water into steam.
Answer: Conversion of water into steam is boiling.

Question 6.
Give two examples for each of the following:
(a) Substances which sublime.
(b) Substances which do not change their states.
(c) Substances which are rigid and not compressible.

(a) Naphthalene, camphor, dry ice.
(b) Oxygen, hydrogen, nitrogen
(c) Glass, stone, pen.

Question 7.
Fill in the blanks with the correct words from the bracket.

  1. From the three states of matter, ______ (solids / liquids / gases) expand the least.
  2. Brownian movement is maximum in _______  (gases / solids / liquids).
  3. Cohesive forces are negligible in _______ (liquids / solids / gases)
  4. Matter can change from one state to another by change in ________ [temperature or pressure /temperature only].
  5. The space between atoms’ [molecules] of solids is ________ [minimum / maximum].
  6. Intermingling of molecules is called ________ [perforation / diffusion].
  7. Ice on absorption of heat converts to ‘X’ a process called [vaporization / melting]. ‘X’ changes to water vapour on  ______    [heating / cooling]. Water vapour changes back to ‘X’ on  _______    [freezing / condensation]. The constant temperature at which ice changes into ‘X’ is called its  ________    [fusion point / melting point / boiling point].
  8. Solids and liquids have a definite volume but gases do not.
  9. The space between atoms in gases is maximum while in solids is minimum
  10. Conversation of a vapour into a liquid is called condensation.
  11. Wax, sugar is an example of a crystalline substance.
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