Chemical Kinetics NEET Previous Year Questions (PYQs)
Practice important NEET previous year questions from Chemical Kinetics. These chapter-wise MCQs are selected from past NEET exams with answers and clear explanations.
👉 Read theory first:
Chemical Kinetics Class 12 Notes
Q1. The correct difference between first and second order reactions is that:
(NEET 2018)
- (A) Rate of first order does not depend on concentration
- (B) Half-life of first order is independent of initial concentration
- (C) Second order reactions cannot be catalysed
- (D) Rate of second order does not depend on concentration
Show Answer
(B)
Show Explanation
Half-life of a first order reaction is independent of initial concentration, while for second order it depends on concentration.
Q2. When initial concentration of a reactant is doubled, the half-life of a zero order reaction:
(NEET 2018)
- (A) is halved
- (B) is doubled
- (C) remains unchanged
- (D) is tripled
Show Answer
(B)
Show Explanation
For zero order reactions, half-life is directly proportional to initial concentration.
Q3. The overall rate of a reaction depends on:
(NEET 2017)
- (A) Fastest step
- (B) Intermediate concentration
- (C) Slowest step
- (D) Catalyst concentration
Show Answer
(C)
Show Explanation
The slowest step in a reaction mechanism is the rate-determining step.
Q4. A first order reaction has rate constant 10−2 s−1. Time required for 20 g of reactant to reduce to 5 g is:
(NEET 2017)
- (A) 138.6 s
- (B) 346.5 s
- (C) 693.0 s
- (D) 238.6 s
Show Answer
(A)
Show Explanation
Reduction from 20 g to 5 g involves two half-lives.
t = 2 × (0.693 / k) = 138.6 s.
Q5. The rate of a first order reaction decreases from 0.04 to 0.03 mol L−1s−1 in 10 s. The half-life is:
(NEET 2016)
- (A) 24.1 s
- (B) 34.1 s
- (C) 44.1 s
- (D) 54.1 s
Show Answer
(C)
Show Explanation
Using first order integrated rate law, the half-life comes out to be approximately 44.1 s.
Q6. Addition of a catalyst affects which of the following?
(NEET 2016)
- (A) Enthalpy change
- (B) Internal energy
- (C) Activation energy
- (D) Free energy change
Show Answer
(C)
Show Explanation
A catalyst provides an alternate pathway with lower activation energy.
Q7. If the unit of rate constant is mol L−1s−1, the order of reaction is:
(NEET 2015)
- (A) First
- (B) Second
- (C) Zero
- (D) Third
Show Answer
(C)
Show Explanation
Zero order reaction has units of rate constant as mol L−1s−1.
Q8. Activation energy can be calculated from the slope of:
(NEET 2015)
- (A) k vs T
- (B) ln k vs 1/T
- (C) k vs 1/T
- (D) ln k vs T
Show Answer
(B)
Show Explanation
From Arrhenius equation, slope of ln k vs 1/T = −Ea/R.
Q9. If half-life of a reaction is independent of initial concentration, the reaction is:
(NEET 2015)
- (A) First order
- (B) Second order
- (C) Zero order
- (D) Fractional order
Show Answer
(A)
Show Explanation
Half-life independent of concentration is a property of first order reactions.
Q10. Time required for 99% completion of a first order reaction is:
(NEET 2019)
- (A) 0.693/k
- (B) 2.303/k
- (C) 4.606/k
- (D) 6.909/k
Show Answer
(D)
Show Explanation
For 99% completion of first order reaction, time = 6.909 / k.
Q11. Order of a reaction can be:
(NEET 2011)
- (A) Zero only
- (B) Fractional only
- (C) Always whole number
- (D) Zero, fractional or negative
Show Answer
(D)
Show Explanation
Order of reaction may be zero, fractional or even negative.
Q12. Unit of rate constant for zero order reaction is:
(NEET 2011)
- (A) s−1
- (B) mol L−1s−1
- (C) L mol−1s−1
- (D) s
Show Answer
(B)
Show Explanation
Zero order reaction rate constant has units of concentration per time.
Q13. Rate constant of a reaction depends on:
(NEET 2010)
- (A) Concentration
- (B) Temperature
- (C) Pressure
- (D) Catalyst amount
Show Answer
(B)
Show Explanation
Rate constant depends only on temperature.
Q14. For zero order reaction, concentration vs time graph is:
(NEET)
- (A) Exponential
- (B) Straight line
- (C) Hyperbolic
- (D) Parabolic
Show Answer
(B)
Show Explanation
In zero order reactions, concentration decreases linearly with time.
Q15. Enzymes increase reaction rate by:
(NEET 2000)
- (A) Increasing activation energy
- (B) Lowering activation energy
- (C) Changing equilibrium
- (D) Increasing entropy
Show Answer
(B)
Show Explanation
Enzymes act as biological catalysts and lower activation energy.
Q16. Rate of reaction is maximum when:
(NEET)
- (A) Reactant concentration is maximum
- (B) Reactant concentration is minimum
- (C) Equilibrium is reached
- (D) Reaction is completed
Show Answer
(A)
Show Explanation
Reaction rate is maximum at the beginning when reactant concentration is highest.
Q17. Temperature coefficient of a reaction is defined as:
(NEET)
- (A) Increase in temperature by 10 K
- (B) Ratio of rate constants at temperatures differing by 10 K
- (C) Activation energy
- (D) Collision frequency
Show Answer
(B)
Show Explanation
Temperature coefficient is the ratio of rate constants at two temperatures differing by 10 K.
Q18. In Arrhenius equation, pre-exponential factor represents:
(NEET)
- (A) Activation energy
- (B) Collision frequency
- (C) Threshold energy
- (D) Entropy change
Show Answer
(B)
Show Explanation
Pre-exponential factor represents frequency of effective collisions.
Q19. For first order reaction, the plot of ln[A] vs time is:
(NEET)
- (A) Straight line with positive slope
- (B) Straight line with negative slope
- (C) Curve
- (D) Parallel to x-axis
Show Answer
(B)
Show Explanation
For first order reactions, ln[A] vs time gives a straight line with negative slope.
Q20. For second order reaction, half-life is proportional to:
(NEET)
- (A) Initial concentration
- (B) Square of concentration
- (C) Inverse of concentration
- (D) Independent of concentration
Show Answer
(C)
Show Explanation
For second order reactions, half-life is inversely proportional to initial concentration.
👉 More Chemical Kinetics NEET PYQs will be added gradually.