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प्रश्न
Why energy is involved in a chemical change?
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उत्तर
In every chemical change, change in energy is involved.
There is a difference between the chemical energies of the reactants and products. It involves the breaking up of chemical bonds between the atoms resulting in the absorption of energy in the form of heat and simultaneous formation of bonds with the release of energy.
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संबंधित प्रश्न
Define exothermic reactions. Give two examples of each.
State the effect of an endothermic reaction.
Identify the endothermic and exothermic reaction.
\[\ce{CaCO_{3(s)}->[\Delta] CaO_{(s)} + CO2}\]
Complete the following statement.
On heating, hydrated copper sulphate changes its colour from ________ to __________.
Give an example of an endothermic reaction.
Give an example with a balanced equation, of the following reaction:
photochemical reaction
Assertion: A drop of petrol when touched with finger gives a chill feeling.
Reason: The above phenomenon is an endothermic one.
Match the following:
| Colum I | Column II | ||
| 1. | Alloying | a. | Exothermic change |
| 2. | Crystallization | b. | Periodic change |
| 3. | Soap powder + water | c. | Mixing of molten solids |
| 4. | Seasonal changes | d. | Pure solid |
Give scientific reason.
While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is added slowly to water with constant stirring.
Give scientific reasons.
While preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory, the concentrated sulphuric acid is added slowly to water with constant stirring.
