Question

i. Give two differences between a physical change and a chemical change. ii. Explain whether condensation of water vapour is a physical or a chemical change. iii. Write word equations for the following reactions: a. Breaking down/ electrolysis of water b. synthesis of water c. decomposition of sugar d. photosynthesis in plants

Answer 1

Answer:A physical change can be reversed but a chemical change cannot be reversed.

In a physical change,no new products are formed but in a chemical change new products are formed.

Condensation of water vapour is a physical change because no new products are formed

Explanation:

Answer 2

Answer:

1)In a physical change, the molecules are rearranged while their actual composition remains same. In a chemical change, the molecular composition of a substance completely changes and a new substance is formed. Some example of physical change are freezing of water, melting of wax, boiling of water, etc.

2)Physical Change bcz we can reverse it.

3)

a  )2 H2O(l) → 2 H2(g) + O2(g) 

b) 2H2(g) + O2(g) → 2H2O(l ) 

c) C12H22O11 (s) + H2SO4 (aq) + 1/2 O2 (g) → 11 C (s) + CO2 (g) + 12 H2O (g) + SO

d )6 CO2 + 6 H2O + light --> C6H12O6 + 6 O2