1 (a) What: is a chemical reaction?
(b) State the conditions necessary for a chemical change or reaction.
Solution

2 Define the following terms
(a) Chemical change
(b) Chemical bond
(c) Effervescence
(d) Precipitate
Solution

3 Give an example of a reaction where the following are involved
(a) Heat (b) Light (c) Electricity (d) Close contact (e) Solution (f) Pressure (g) Catalyst
Solution

4 Define :
(a) Photochemical reaction (b) Electrochemical reaction. Give one example in each
Solution

5 Give an example of each of the following chemical changes.
(a) A photochemical reaction involving
(i) silver salt (ii) water
(b) A reaction involving
(i) blue solution
(ii) formation of a dirty green precipitate
(c) Two gases combine to form a white solid.
(d) Two solids combine to form a liquid.
(e) A reaction where color change is noticed.
Solution

6 Write the chemical reaction where the following changes observed.
a) Gas is evolved
b) Colour change is noticed
c) Precipitate is formed
d) Physical state is changed
Solution

7 Give a reason for the following :
(a) Silver nitrate solution is kept in coloured bottles.
(b) Molybdenum is used in the manufacture of ammonia.
(c) A blue solution of copper sulphate changes to green when a piece of iron is added to this solution.
(d) Colourless concentrated sulphuric acid in a test tube changes to blue on adding a small piece of copper to it.
Solution