Formation of curd from milk is the example of
(a) slow
(b) chemical change
(c) periodic change
(d) physical change

Q. Match the following.

(a) Evaporation of water	(i) Non-periodic change
(b) Milk turning sour	(ii) Periodic change
(c) Earthquake	(iii) Chemical change
(d) Change of seasons	(iv) Physical change
(e) Glowing of bulb	(v) Reversible change

Q. Melting of wax and heating of blade are the examples of
(a) physical change
(b) chemical change
(c) periodic change
(d) irreversible change

Q. Write True (T) or False (F) against the following statements in the given brackets:
1. Souring of milk is a physical change. ( )
2. Digestion of food is a physical change. ( )
3. Crystallisation is widely used to prevent rusting. ( )
4. Formation of steam from water on heating is a physical change. ( )
5. Glowing of the filament of a bulb is an example of a chemical change. ( )

Q. Classify the following into slow and fast changes:
(i) Spinning of top
(ii) Formation of day and night
(iii) Formation of curd from milk
(iv) Change of season
(v) Making curd from milk by adding lemon juice.