Rates of Chemical Reaction Practice Questions
WAEC (West Africa) · WAEC Chemistry · 142 free MCQs with instant results and detailed explanations.
142
Total
42
Easy
73
Medium
27
Hard
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Sample Questions from Rates of Chemical Reaction
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Q1
Easy
Which factor does NOT affect the rate of a chemical reaction?
A.
Concentration of reactants
B.
Presence of a catalyst
C.
Color of the reactants
D.
Temperature of the reaction
Show Answer & Explanation
Correct Answer: C
The color of the reactants does not influence the rate of a chemical reaction, unlike concentration, temperature, and catalysts, which significantly affect reaction rates.
Q2
Easy
When the temperature of a reaction is increased, what typically happens to the rate of the reaction?
A.
It decreases
B.
It remains the same
C.
It increases
D.
It becomes unpredictable
Show Answer & Explanation
Correct Answer: C
Increasing the temperature generally increases the kinetic energy of the molecules, leading to more frequent and effective collisions, thereby increasing the rate of the reaction.
Q3
Easy
If the concentration of a reactant in a reaction is doubled, what is likely to happen to the rate of that reaction?
A.
It will halve
B.
It will double
C.
It will remain unchanged
D.
It will quadruple
Show Answer & Explanation
Correct Answer: B
According to the collision theory, doubling the concentration of a reactant typically leads to an increase in the number of collisions, which in turn doubles the rate of the reaction.
Q4
Medium
What is the effect of increasing temperature on the rate of a chemical reaction?
A.
Increases the rate by providing more energy to reactants
B.
Decreases the rate due to higher energy collisions
C.
Has no effect on reaction rate
D.
Only affects gaseous reactions
Show Answer & Explanation
Correct Answer: A
Increasing temperature provides reactant molecules with more kinetic energy, leading to more frequent and effective collisions, thus increasing the reaction rate.
Q5
Medium
In the reaction: 2H2 + O2 → 2H2O, if the concentration of H2 is doubled, what happens to the rate of reaction?
A.
The rate halves
B.
The rate remains unchanged
C.
The rate doubles
D.
The rate quadruples
Show Answer & Explanation
Correct Answer: C
According to the rate law, if the concentration of a reactant is increased, the rate of reaction increases proportionally, thus doubling the concentration of H2 will double the rate.
Q6
Medium
Which of the following factors does NOT affect the rate of a chemical reaction?
A.
Nature of the reactants
B.
Presence of a catalyst
C.
Color of the reactants
D.
Temperature
Show Answer & Explanation
Correct Answer: C
The color of the reactants does not influence the reaction rate, whereas the other factors directly affect how quickly a reaction proceeds.
Q7
Medium
How does a catalyst affect the activation energy of a reaction?
A.
Increases activation energy
B.
Lowers activation energy
C.
Has no effect on activation energy
D.
Changes the reaction products
Show Answer & Explanation
Correct Answer: B
A catalyst provides an alternative reaction pathway with lower activation energy, which increases the reaction rate without being consumed in the process.
Q8
Hard
What effect does increasing the concentration of reactants have on the rate of a bimolecular reaction?
A.
Increases the rate due to more frequent collisions.
B.
Decreases the rate due to greater crowding.
C.
Has no effect on the rate of reaction.
D.
Increases the activation energy.
Show Answer & Explanation
Correct Answer: A
Increasing the concentration of reactants leads to more molecules being available for collisions, thus increasing the frequency of effective collisions and consequently the rate of the reaction.
Q9
Hard
If the rate of a chemical reaction doubles when the temperature is increased from 25°C to 35°C, what can be inferred about the activation energy of the reaction?
A.
It is low, indicating that temperature changes greatly affect the rate.
B.
It is high, meaning that temperature has a minimal effect on the rate.
C.
It is variable, changing with temperature.
D.
It cannot be determined from the given information.
Show Answer & Explanation
Correct Answer: A
A low activation energy implies that a small increase in temperature can lead to a significant increase in reaction rate, as evidenced by the doubling of the rate when the temperature was increased by 10°C.
Q10
Hard
Which of the following factors does NOT affect the rate of a chemical reaction?
A.
Concentration of reactants
B.
Temperature of the reaction
C.
Catalyst presence
D.
Color of the reactants
Show Answer & Explanation
Correct Answer: D
The color of the reactants does not influence the rate of a chemical reaction. The rate is typically affected by concentration, temperature, and the presence of catalysts.
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Rates of Chemical Reaction — WAEC (West Africa) WAEC Chemistry Practice Questions Online
This page contains 142 practice MCQs for the chapter Rates of Chemical Reaction in WAEC (West Africa) WAEC Chemistry. The questions are organized by difficulty — 42 easy, 73 medium, 27 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.