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All questions of Chemical Changes and Reactions for Class 9 Exam
What is an example of an endothermic reaction?- a)Reaction of zinc with hydrochloric acid
- b)Decomposition of calcium carbonate
- c)Formation of ammonia from nitrogen and hydrogen
- d)Combustion of hydrogen
Correct answer is option 'B'. Can you explain this answer?
What is an example of an endothermic reaction?
a)
Reaction of zinc with hydrochloric acid
b)
Decomposition of calcium carbonate
c)
Formation of ammonia from nitrogen and hydrogen
d)
Combustion of hydrogen
 | EduRev Class 9 answered |
The decomposition of calcium carbonate into calcium oxide and carbon dioxide is an endothermic reaction, meaning it absorbs heat from the surroundings. This is typically observed when calcium carbonate is heated to high temperatures.
Which factor is NOT required for a chemical reaction to occur?- a)Energy supply
- b)Collision of particles
- c)Presence of a catalyst
- d)Constant temperature
Correct answer is option 'A'. Can you explain this answer?
Which factor is NOT required for a chemical reaction to occur?
a)
Energy supply
b)
Collision of particles
c)
Presence of a catalyst
d)
Constant temperature
 | Pranab Chawla answered |
Understanding Chemical Reactions
In a chemical reaction, certain factors are necessary for the reaction to take place. However, not all of them are essential. Let's explore why a constant energy supply is not required.
Key Factors for Chemical Reactions
- Collision of Particles:
- Reactions occur when particles collide with sufficient energy.
- The frequency and orientation of these collisions affect the reaction rate.
- Presence of a Catalyst:
- Catalysts speed up reactions without being consumed.
- They lower the activation energy required, facilitating faster reactions.
- Constant Temperature:
- While temperature can influence reaction rates, it is not a strict requirement.
- Reactions can occur at varying temperatures; some might even be spontaneous at lower temperatures.
Why Energy Supply is Not Required
- Energy does play a role in overcoming activation energy barriers, but it does not need to be continuously supplied during the reaction.
- For example, once a reaction starts, it may produce its own energy (exothermic reactions), allowing it to continue without additional energy input.
Conclusion
In summary, while energy, particle collision, and catalysts are important for chemical reactions, a constant energy supply is not essential. Reactions can initiate and proceed under different conditions, making option 'A' the correct answer.
In a chemical reaction, certain factors are necessary for the reaction to take place. However, not all of them are essential. Let's explore why a constant energy supply is not required.
Key Factors for Chemical Reactions
- Collision of Particles:
- Reactions occur when particles collide with sufficient energy.
- The frequency and orientation of these collisions affect the reaction rate.
- Presence of a Catalyst:
- Catalysts speed up reactions without being consumed.
- They lower the activation energy required, facilitating faster reactions.
- Constant Temperature:
- While temperature can influence reaction rates, it is not a strict requirement.
- Reactions can occur at varying temperatures; some might even be spontaneous at lower temperatures.
Why Energy Supply is Not Required
- Energy does play a role in overcoming activation energy barriers, but it does not need to be continuously supplied during the reaction.
- For example, once a reaction starts, it may produce its own energy (exothermic reactions), allowing it to continue without additional energy input.
Conclusion
In summary, while energy, particle collision, and catalysts are important for chemical reactions, a constant energy supply is not essential. Reactions can initiate and proceed under different conditions, making option 'A' the correct answer.
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