Question

Give one example in each case

▪ (a) Change which occurs on heating but can be reversed.

▪ (b) Change which occurs on heating but cannot be reversed.

▪ (c) Change which occurs on cooling but can be reversed.

▪ (d) Change which occurs on mixing two substances, but can be reversed.

▪ (e) Change which occurs on mixing two substances, but cannot be reversed.​

Answer 1

1. Boiling water
2. Burning of coal
3. Freezing ice

Answer 2

Answer:

a) Boiling of milk

b) Baking of chappati

c) Cooling of water to make ice

d) Mixing of Salt and water

e) Mixing lemon and water to make lemonade

MORE TO KNOW -

• Changes in which the initial property of substances does not changes and no new substanve formed is called physical change

• Changes in which initial property of substanves changes and new substance forme is called chemical changes

• Whenever a chemical changes occur it is siad that chemical reaction happen.

• In chemical changes , the bond between the atoms of substance break down and make new bond with atom of another substances.

• Reversible changes - Changes in which we can get the same substances is called reversible .

for ex. Melting of ice

• Irreversible changes - Changes in which we can not get the substance back is called irreversible

for ex. formation of curd