Chemical Kinetics Quiz - CBSE Class 12 Chemistry
Free practice quiz: Chemical Kinetics (CBSE Class 12 Chemistry). 17 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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What is the unit of rate constant (k) in a first-order reaction?
- mol/L.s
- s^-1
- L^2/mol.s
- mol^2/L^2.s
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Answer: B. s^-1
For a first-order reaction, the rate constant has a unit of 's^-1' which reflects the change in concentration over time.
The rate of a reaction generally increases with increase in temperature due to:
- Increased molecular collisions
- Decreased activation energy
- Change in pH
- Reduction in volume
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Answer: A. Increased molecular collisions
As temperature increases, molecules move faster, leading to more frequent collisions, thus increasing the reaction rate.
If a reaction is zero-order, what is the effect of concentration on the rate of the reaction?
- Rate increases linearly with concentration
- Rate decreases with concentration
- Rate is constant
- Rate depends on temperature only
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Answer: C. Rate is constant
In a zero-order reaction, the rate of reaction is constant and does not depend on the concentration of reactants.
In a chemical reaction, which of the following factors can lead to a change in the activation energy?
- Change in temperature
- Change in pressure
- Use of a catalyst
- Change in the color of the reactants
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Answer: C. Use of a catalyst
A catalyst provides an alternative pathway for the reaction with a lower activation energy, affecting the rate.
How does a graph of concentration versus time appear for a zero-order reaction?
- Linear decrease
- Exponential decrease
- Constant
- Parabolic curve
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Answer: A. Linear decrease
In a zero-order reaction, the concentration decreases linearly over time, indicating a constant rate of reaction.