Page 26 - ICSE Chemistry 8

3. Write any two proper es of solids.
4. What does the law of conserva on of mass state?
5. Give an example to show conserva on of mass.

AT LENGTH

A. Diff eren ate between the following.
1. Solids, liquids and gases

2. Intermolecular force of a rac on and intermolecular space
3. Conserva on of mass during a physical change and conserva on of mass during a chemical change

B. Read the following paragraph. Iden fy the incorrect parts.
The law of construc on of mass states that mass cannot be created but destroyed. The density of ma er
and the volume occupied by the ma er remain constant within a system but the mass may vary. The law
of conserva on of mass does not hold because the naturally occurring elements are not stable The atom
itself can be created or destroyed.

C. Answer in detail.

1. Write the postulates of the kine c molecular theory of ma er.
2. Explain why the par cles in gases can move away from each other in context to kine c molecular
theory of ma er.

3. What happens when wood is burnt in air?
4. With the help of an ac vity, show that mass remains same during a physical change.

5. With the help of an ac vity, show that mass remains same during a chemical change.

6. Show that total mass of reactants is equal to the total mass of products in a chemical reac on
between barium chloride and sodium sulphate.

OBSERVE AND PERFORM

A. Observe the given image carefully and answer the following ques ons.

(i) (ii) (iii)

1. Iden fy the states of ma er on the basis of the arrangement of par cles.
2. Arrange these states of ma er in descending order on the basis of intermolecular space and
intermolecular force of a rac on.

12