Question

which of the following is not a physical change (I) melting of ice (ii) breaking of glass (iii) boiling of water (iv) rusting of iron​

Answer 1

Answer:-

Option ( iv ) is a chemical change but others are physical change

step-by-step explanation:

( i ) Melting of ice

Answer:-

⟶ Melting of ice is a physical change

Reason:-

• When, water is cold cold it freezes to form ice. When left in open ice melts and changes back to water. Similarly, when water is boiled it changes to water vapour and when the water vapour is cooled, it condenses back to liquid water this means that the change of states in all cases is temporary and reversible.
• The composition of the substance doesn't change.
• There is no energy change.
• No new substances are produced or formed.
• There is only for change in physical properties of the substance.

( ii ) Breaking of glass

Answer:-

⟶ Breaking of glass is a physical change.

Reason:-

• When glass tumbler breaks it forms many pieces each broken piece of the glass objects is still glass. So, no new substances are produced or formed.
• The change is temporary.
• There is no change in Energy.

( iii ) Boiling of water

Answer:-

⟶ Boiling of water is a physical change.

Reason:-

• When water is boiled it changes to water vapour and when the water vapour is cooled, it condenses back to liquid water this means that the change of states in all cases is temporary and reversible.
• The change is temporary.
• No new substances are formed or produced.
• There is a change in physical properties of the substance.

( iv ) Rusting of iron

Answer:-

⟶ Rusting of iron is a chemical change.

Reason:-

• When, a piece of iron is left out in moist air it slowly changes into a dull brittle brown substance called rust . The composition and properties of iron different from those of iron.
• We cannot get back the iron in it's original form, So Rusting of iron is an irreversible change.
• This change is permanent.
• New substances are formed.
• Energy is given out during this change but it is very small.

↪More Information↩

• Some more examples of physical change are:-

1. Melting of wax
2. Ringing of an electric bell
3. Sublimation of iodine
4. Dissolution of of sodium chloride in water
5. Evaporation of water
6. Freezing of water
7. Magnetizing of a piece of iron
8. Glowing of an electric bulb
9. Tearing of paper
10. Stretching of a rubber band

• Some more examples of chemical change are:-

1. Cooking of food
2. Formation of curd from milk
3. Digestion of food
4. Respiration
5. Heating of a sugar
6. Burning of coal
7. Burning of firecrackers
8. Boiling of an egg
9. Photosynthesis
10. Burning of magnesium ribbon