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प्रश्न
When a candle is lit the following changes are observed.
- Wax melts.
- Candle keeps burning.
- The size of the candle decreases.
- The molten wax solidifies
- Which of the changes can be reversed? Justify your answer
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उत्तर
- Wax melting is a reversible change.
- “The molten wax solidifies” is a reversible change.
These two changes can be reversible to get back to the original state. So the above two changes are reversible changes.
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संबंधित प्रश्न
Very Short Answer Type Question:
Some common changes are given in the below Table. Which of these changes do you think can be reversed?
| Change | Can be reversed |
| (i) Raw egg to boiled egg | Yes/No |
| (ii) Batter to idli | |
| (iii) Wet clothes to dirty clothes | |
| (iv) Woollen yarn to knitted sweater | |
| (v) Grain to its flour | |
| (vi) Cold milk to hot milk | |
| (vii) straight string to a cold string | |
| (viii) Bud to flower | |
| (ix) Milk to paneer | |
| (x) Cow dung to biogas | |
| (xi) stretched rubber band to its normal size | |
| (xii) Melting of ice-cream |
An example for reversible change is
Analogy
Curdling of milk : irreversible change :: Formation of clouds : ________change
A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Rusting of iron is a reversible change.
Name the two types of changes.
Look at the figure which shows three situations.
Which of these shows a reversible change and why?
Can we reverse the following change? If yes, suggest the name of the method.
Water into water vapour
Which of the following changes cannot be reversed?
- Blowing of a balloon
- Folding paper to make a toy aeroplane
- Rolling a ball of dough to make roti
- Baking cake in an oven
- Drying a wet cloth
- Making biogas from cow dung
- Burning of a candle
Choose the odd one out. Give a reason for your choice.
