Question

11. Classify the changes involved in the following processes as physical o
(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​

Answer 1

Answer:

(a) Photosynthesis: irreversible, chemical changes.

                6CO2+6H2O⟶C6H12O6+6O2

(b)  Dissolving of water : reversible, physical change.

(c)  Bumping of coal − irreversible, chemical change.

(d)  Melting of wax − reversible by cooling, physical change.

(e)  Physical change as mallacbility (beating metal into then sheets) does not change composition.

(f)  Digestion − chemical change.

Answer 2

Changes occur are:-

a) In Photosynthrsis food is being prepared by leaves - It is a chemical change.

b) Dissolving sugar in Water - Water will become sweet it is a chemical change as it can not be reversed.

c) Burning of coal produces fuel it cantbe reversed it is a physical change.

d) Melting of wax is a physical change as it can be reversed.

e) Beating aluminium foil is a physical change as it can be reversed.

f) Digestion of food is a chemical change that occur in stomach and cannot be reversed.