Question

Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food
NCERT Solutions for Class 7th Science Chapter 6 Physical and Chemical Changes Page 65 Exercise Question 1

Answer 1

(a) Photosynthesis → Chemical change (b) Dissolving sugar in water → Physical change (c) Burning of coal → Chemical change (d) Melting of wax → Physical change (e) Beating aluminium to make aluminium foil → Physical change (f) Digestion of food → Chemical change

Answer 2

Chemical Change and Physical Change

Explanation:

(a) Photosynthesis  = Chemical Change

Explanation - In this process water and carbon change into oxygen so, this change is a chemical change.

(b) Dissolving sugar in water  = Physical Change

Explanation - we can get sugar back by heating the water, so this is a physical change.

(c) Burning of coal  = Chemical Change

Explanation - we can not get coal back by any process, so this is a chemical change.

(d) Melting of wax  = Physical Change

Explanation - we can get wax back by solidify, so this is a physical change.

(e) Beating aluminum to make aluminum foil  = Physical Change

Explanation - In this process, there is no change in the chemical property of aluminum.

(f ) Digestion of food = Chemical Change

Explanation - In this process there is many chemicals engage so it is a chemical change.