1. Answer the following questions.
(1). 'Melting of ice', stretching of a rubber band' are which type of changes?
(2). 'Formation of curd from milk', burning of dry leaves' are which type of changes?
(3). Write 2 examples of irreversible changes?
(4). Write 2 examples of reversible changes?
Answers
Explanation:
(1) In streching of rubber band only the size of the rubber band changes. The rubber band comes back in its original shape and size, once it is released. This is a physical and reversible change
(2). : In the setting of curd, milk changes into new substance, curd. ... Answer: In burning of wood, new substances are formed and hence it is a chemical change. While cutting the wood into small pieces no new substance is formed, thus it is a physical change.
(3). Formation of curd from milk', burning of dry leaves'
(4). Melting of ice', stretching of a rubber band'
→ "melting of ice' and "stretching of rubber band" is a Reversible change.
→ "Formation of curd from milk and "Burning of dry leaves" is a irreversible change.
→ Buring of paper and crumbling of paper.
→ pressing of sponge and crumbling of cloth.
Know more !!
What is a Reversible change ?
→ Reversible change is that change which can be reversed to it's original form again.
→ Reversible change takes less time.
→ No new substance is formed.
→ For example when we melt an ice it comes to it's original form that is water.
What is a irreversible change ?
→ Irreversible change is that change which can not be reversed to it's original form again.
→ In Irreversible change a new substance is always going to be formed.
→ Irreversible change takes long time.
→ For example burning of candle, when we burn a candle it will be totally melted and wax will be left and then we cannot make a new candle from that remaining wax.
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