Q. In a first-order reaction, if the half-life is 10 minutes, what will be the half-life after the concentration is halved?
A.
5 minutes
B.
10 minutes
C.
15 minutes
D.
20 minutes
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Solution
The half-life of a first-order reaction is constant and does not depend on the concentration; it remains 10 minutes.
Correct Answer:
B
— 10 minutes
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Q. In a first-order reaction, if the half-life is 10 minutes, what will be the half-life if the initial concentration is doubled?
A.
10 minutes
B.
20 minutes
C.
5 minutes
D.
15 minutes
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Solution
For a first-order reaction, the half-life is independent of the initial concentration. Therefore, it remains 10 minutes.
Correct Answer:
A
— 10 minutes
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Q. In a reaction where the rate law is rate = k[A]^2[B], what is the overall order of the reaction?
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Solution
The overall order is the sum of the exponents in the rate law: 2 (from [A]^2) + 1 (from [B]) = 3.
Correct Answer:
D
— 4
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Q. In the context of reaction rates, what does the term 'activation energy' refer to?
A.
The energy required to start a reaction
B.
The energy released during a reaction
C.
The energy of the products
D.
The energy of the reactants
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Solution
Activation energy is the minimum energy required for reactants to collide and form products, initiating the reaction.
Correct Answer:
A
— The energy required to start a reaction
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Q. What is the effect of increasing the concentration of reactants on the rate of reaction for a zero-order reaction?
A.
Rate increases
B.
Rate decreases
C.
Rate remains constant
D.
Rate becomes negative
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Solution
For a zero-order reaction, the rate is independent of the concentration of reactants, so it remains constant.
Correct Answer:
C
— Rate remains constant
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Q. What is the effect of temperature on the rate of a chemical reaction according to the Arrhenius equation?
A.
Rate decreases exponentially with temperature
B.
Rate increases linearly with temperature
C.
Rate increases exponentially with temperature
D.
Rate remains constant regardless of temperature
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Solution
According to the Arrhenius equation, the rate constant increases exponentially with an increase in temperature, leading to a higher reaction rate.
Correct Answer:
C
— Rate increases exponentially with temperature
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Q. What is the effect of temperature on the rate of a chemical reaction?
A.
It decreases the rate
B.
It has no effect
C.
It increases the rate
D.
It can either increase or decrease the rate
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Solution
According to the Arrhenius equation, an increase in temperature generally increases the kinetic energy of molecules, leading to a higher reaction rate.
Correct Answer:
C
— It increases the rate
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Q. What is the primary reason for the use of catalysts in industrial processes?
A.
To increase the yield of products
B.
To lower production costs
C.
To increase the reaction rate
D.
To change the reaction pathway
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Solution
Catalysts are primarily used in industrial processes to increase the reaction rate, allowing for more efficient production.
Correct Answer:
C
— To increase the reaction rate
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Q. What is the primary reason for using a catalyst in industrial chemical processes?
A.
To increase the yield of products
B.
To lower the cost of raw materials
C.
To speed up the reaction rate
D.
To change the reaction pathway
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Solution
Catalysts are primarily used to speed up reaction rates, making processes more efficient and cost-effective.
Correct Answer:
C
— To speed up the reaction rate
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Q. What is the role of a catalyst in a chemical reaction?
A.
It increases the activation energy
B.
It decreases the activation energy
C.
It is consumed in the reaction
D.
It changes the equilibrium position
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Solution
A catalyst lowers the activation energy, allowing the reaction to proceed faster without being consumed.
Correct Answer:
B
— It decreases the activation energy
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Q. Which of the following is a characteristic of a reaction at equilibrium?
A.
The concentrations of reactants and products are equal
B.
The rate of the forward reaction equals the rate of the reverse reaction
C.
The reaction has stopped
D.
The temperature is constant
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Solution
At equilibrium, the rates of the forward and reverse reactions are equal, but the concentrations of reactants and products do not have to be equal.
Correct Answer:
B
— The rate of the forward reaction equals the rate of the reverse reaction
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