Question 1 What is a physical change.Give example?
Question 2 What is a chemical change.Give example ?
Question 3 Give the main differences between physical and chemical change?
Physical and Chemical changes
The changes in which no new substance are formed,are called physical changes.
In a physical change,the substances involved do not change their identity.They can be easily returned to their original form by some physical changes.
For Ex:Freezing of water,Boiling of water,Condensation of steam,Making a solution,Glowing of electric bulb,stretching of rubber band,cutting or tearing a piece of paper etc.
The changes in which new substance are formed,are called chemical changes.
In a chemical change,the substances involved change their identity ie they get converted into entirely new substance.
For Ex:Burning of magnesium ribbon,Rusting of iron,Formation of curd from milk,Cooking of food etc.
| Physical change
|| Chemical Change
|1)No new substance is formed in the physical change.
||A new substance is formed in a chemical change.
|2)Physical change is temporary change.
||A chemical change is a permanent change.
|3)Physical change is reversible.
||Chemical change is irreversible.
|4)Very little heat or light energy is usually absorbed or given out in a physical change
||A lot of heat or light energy is absorbed or given out in a chemical change.
|5)The mass of a substance does not alter in a physical change
||The mass of a substance does alter in a chemical change.