Page 70 - ICSE Chemistry 6

Quick Review

• Ma er has mass and occupies space.
• Ma er exists in three states—solid, liquid and gas. These three states of ma er are diff erent because
the molecules present in them are arranged in diff erent ways.

• The intermolecular force of a rac on decreases as the distance between the molecules increases.
• Solids have defi nite shape, mass and volume.
• Liquids have defi nite volume but not fi xed shape and they are free fl owing.
• Gases neither have defi nite shape nor defi nite volume and they can move in all direc ons.
• The diff erence in proper es of states of ma er is due to intermolecular space, cohesive forces and
random mo on of par cles (diff usion and Brownian mo on).
• On hea ng a substance, following things take place: change in states of ma er, thermal expansion of
the substance and chemical change.

EXERCISES

BE PROMPT

A. Fill in the blanks.

1. Mass is the measure of ___________ of ma er contained in a substance.
2. _____________ is a force that tends to oppose mo on.
3. Liquids are _______________ because the molecules are loosely packed.
4. In gases, the intermolecular forces between the molecules are very ____________.

5. The space between the molecules of a substance is called ______________________________.
6. _____________ is the gaseous state of a solid.

B. State whether the following statements are true (T) or false (F).
1. Ma er is composed of extremely small par cles.
2. A molecule has an independent existence and also exhibits all the proper es of ma er.
3. Liquids have strong forces of a rac on.

4. Solids have less density than liquids.
5. The par cles in gases move rapidly in all direc ons.
6. Brownian mo on is caused by the collision of molecules.

C. Choose the correct op on.
1. Which of the following statements is not true for mass?
(a) It is the quan ty of ma er. (b) It is constant everywhere.
(c) It is the amount of force of gravity ac ng on the mass.
(d) It cannot be zero.
2. __________ refers to the intermingling of par cles of diff erent substances on their own.
(a) Combining (b) Mixing (c) Refi ning (d) Diff usion

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