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प्रश्न
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
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उत्तर
In this case, the changes cannot be reversed. This is because the cement that hardens up after getting wet cannot be obtained back.
संबंधित प्रश्न
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction is a chemical reaction in which there is
- removal of hydrogen
- removal of oxygen
- addition of oxygen
- none of these
True or false
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State the conditions necessary for a chemical change or reaction.
Give an example of a reaction where the following are involved:
Close contact
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Give an example of the following chemical change.
Two gases combine to form white solid
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Give a word equation for the following reaction.
An exothermic reaction where both the reactants are gases, one of which is oxygen.
