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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
True or false
New substances are formed in a chemical change.
Write true or false :
No new substance is formed during a chemical reaction.
Give an example of a reaction where the following are involved
Heat
Explain the Silver nitrate solution is kept in coloured reagent bottles in the laboratory.
State the following reaction represent oxidation or reduction.
\[\ce{Fe++->Fe+++}\]
State the following reaction represent oxidation or reduction.
\[\ce{Ag->Ag+}\]
Select the correct answer from the options given below:
State the gaseous product formed, when
An active metal reacts with dilute sulphuric acid.
Which of the following is/are true when milk changes into curd?
- Its state is changed from liquid to semi solid.
- It changes colour.
- It changes taste.
- The change cannot be reversed.
Choose the correct option from below:
The simplest method of preventing rusting of iron is to coat it with oil, grease, or paint. The reason being ______.
Magnesium + oxygen → magnesium oxide.
2Mg + O2 → 2Mg O
