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Hots Questions: Think and Answer.

1) Tearing of paper is irreversible. It is, therefore, a chemical change. Do you agree? Give reasons.

2)  A potato remains a potato even after it is cooked. therefore, cooking is a physical change. Do you agree? Give reasons.

3) When sugar dissolves in water, it disappears. that means it must have changed into a new substance. Therefore, dissolving is a chemical change. Do you agree? Give reasons.

Dear Student

The answers given by your friend Sayantani are correct, I just want to make a correction in the first part i.e. Tearing of paper is a irreversible process but is physical process, as after tearing also the composition of paper is not changing.

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1) Yes. You can't bring it back to its original state through physical methods. Hence it is a chemical change.

2) No. After cooking the properties of a potatro changes, and you can't bring it back to its original state through physical methods. Hence it is a chemical change.

3)No. When sugar dissolves it doesn't dissapear but break up in to fine particles and fill the gaps between the molecules of water and sugar can be got back by evaporation or distillation, both of which are physical methods. Hence it is a physical change.

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Thank you very much for helping

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1) yes i agree because if we burn a paper it cannot be become paper again

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1) Yes. You can 't bring it back to its original state through physical methods. Hence it is a chemical change.

2) No. After cooking the properties of a potatro changes, and you can 't bring it back to its original state through physical methods. Hence it is a chemical change.

3)No. When sugar dissolves it doesn 't dissapear but break up in to fine particles and fill the gaps between the molecules of water and sugar can be got back by evaporation or distillation, both of which are physical methods. Hence it is a physical change.

 

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