CLASS 7 PHYSICAL AND CHEMICAL CHANGES
1. State whether the following statements are true or false:
 (a) When a candle burns, both physical and chemical changes take place.
 (b) Anaerobic bacteria digest animal waste and produce biogas.
(c) Ships suffer a lot of damage though they are painted.
 (d) Stretching of rubber band is not a physical change.

 2. Melting of wax is a change where a solid changes to liquid state. Give one more such change which you observe in your surroundings.

3. What kind of change is shown by tearing of paper?

SHORT ANSWER QUESTIONS
4. Fill in the blanks in the following statements using the words given in the box.
 rusted, colourful, substance, chemical, physical, reversible, iron oxide, object
 (a) Making sugar solution is a ____________ change.
(b) A physical change is generally____________.
 (c) Grinding of wheat grain changes its size. It is a ____________ change.
 (d) Iron benches kept in lawns and gardens get____________. It is a _________ change because a new _________ is formed.

 5. Classify the following processes into physical or chemical changes:
 (i) Beating of aluminium metal to make aluminium foil.
 (ii) Digestion of food.
(iii) Cutting of a log of wood into pieces.
 (iv) Burning of crackers.

 6. Write word equations for two chemical reactions with the help of materials given in the box
. Air, copper sulphate, iron, vinegar, iron oxide, carbon dioxide, iron sulphate, copper, lime water, water

7. Explain the following:
(a) Lime water turns milky on passing carbon dioxide gas into it
. (b) Bubbles are produced when acetic acid is added to a solution of sodium hydrogencarbonate.