Science Important Questions
Changes Around Us
1. Name some of the changes that are taking place around us on their own.
Ans. Changes taking place around us on their own are called natural changes. Some of these are:
1) Falling of leaves
2) Ripening of fruits
3) Rusting of iron
4) Formation of clouds
5) Souring of milk
6) Growth of a plant
2. Define reversible changes. Give examples.
Ans. Changes which reverse back to the original form are called reversible changes.
Examples:
1) Boiling of water
2) Blowing of a balloon
3) Folding a paper
4) Washing of clothes
5) Melting of wax
3. Define irreversible changes. Give examples.
Ans. Changes which do not reverse back to the original form are called irreversible changes.
Examples:
1) Cooking of food
2) Rusting of iron
3) Burning of paper
4) Bursting of a balloon
5) Growth of a plant
4. How is iron blade in agricultural tools fixed to the wooden handle?
Ans. The ring of iron blade is made slightly smaller in size than the wooden handle. To fix the handle, the ring is heated and it expands. Now the handle easily fits into the ring. When the ring cools down, it contracts and fits tightly on the handle.
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