Chemical KineticsNEET MCQs with solutions
Chemical Kinetics covers rate of reaction, rate law, order of reaction, integrated rate equations (zero and first order), half-life, Arrhenius equation and collision theory. NEET tests first-order kinetics calculations, half-life problems, and Arrhenius equation application — numerical questions dominate.
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- 12 Chemistry
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- 24 questions
- In the RankUp app
- 552 questions
- ELITE questions
- 222
- NCERT topics
- 11
Practise 24 questions
Tap an option to check it. Questions from every NCERT topic in this chapter, from easy to hard.
Q1Important PYQ Mixed Concepts
For a first-order reaction, if the half-life is 1 minute, the time required for the reactant concentration to become approximately 6.25% of its initial value is:
Not quite — the answer is D.
6.25% = 1/16 = (1/2)^4, so four half-lives are required. Therefore t = 4 × 1 = 4 min. Option A gives two half-lives (25% remaining). Option B gives three half-lives (12.5% remaining). Option C is a non-standard value with no mathematical basis here.
Q2Important PYQ Mixed Concepts
Which of the following correctly represents the Arrhenius equation relating rate constant k and temperature T?
Not quite — the answer is C.
The Arrhenius equation is k = Ae^(−Ea/RT). The negative sign ensures k increases with temperature. Option A omits the negative sign, incorrectly predicting k decreases with temperature. Option B is an additive form with no theoretical basis. Option D is algebraically invalid.
Q3Mixed Revision
The rate law of a reaction is always determined by
Not quite — the answer is A.
Rate law cannot be predicted from stoichiometry or molecularity — it must be determined experimentally. Option B is the most common trap — students assume balanced equation coefficients give the rate law, which is only true for elementary reactions. Option C (molecularity) applies only to elementary steps, not overall reactions.
Q4Mixed Revision
Molecularity of a reaction is defined only for
Not quite — the answer is B.
Molecularity is the number of molecules colliding in a single elementary step — it has no meaning for overall multi-step reactions. Option A is the trap — students confuse order (which applies to overall reaction) with molecularity. Option D is wrong — molecularity and order are different quantities.
Q5Grand Test
For the reaction 4A + 3B → 6C + 9D, if the rate of formation of C is 6 × 10⁻² mol L⁻¹ s⁻¹, the rate of reaction is:
Not quite — the answer is A.
Rate = (1/6) × d[C]/dt = (1/6)(6 × 10⁻²) = 1 × 10⁻² mol L⁻¹ s⁻¹. The stoichiometric coefficient of C is 6, so the rate of reaction is one-sixth the rate of formation of C. Options B, C, D all omit the factor of 1/6.
Q6Grand Test
A first-order reaction has a half-life of 1 min. The time required for 99.9% completion is approximately:
Not quite — the answer is B.
99.9% completion means 0.1% reactant remains. (1/2)^10 = 1/1024 ≈ 0.098%, so approximately 10 half-lives are required. Time = 10 × 1 = 10 min. Option A (5 half-lives) leaves about 3.1%. Options C and D overestimate.
Q7Rate of Reaction
Rate of a chemical reaction is defined as the change in concentration of a reactant or product per unit
Not quite — the answer is A.
Rate of reaction = Δ[concentration]/Δt, giving units of mol L⁻¹ s⁻¹. Volume and temperature are external conditions, not the divisor in the rate expression. Pressure applies only to gaseous systems and is not the standard definition.
Q8Rate of Reaction
Average rate of reaction differs from instantaneous rate in that it is measured over
Not quite — the answer is B.
Average rate = Δ[A]/Δt over a measurable finite interval. Instantaneous rate uses dt→0 (tangent method). Options A and C describe instantaneous rate, not average rate.
Q9Factors Affecting Rate of Reaction
Which of the following increases the rate of reaction by increasing the frequency of effective collisions between reactant molecules?
Not quite — the answer is A.
Higher concentration places more molecules per unit volume, directly increasing collision frequency and thus the number of effective collisions per second. Adding an inert gas at constant volume does not change reactant partial pressures or concentrations. Decreasing pressure reduces collision frequency.
Q10Factors Affecting Rate of Reaction
The exponential dependence of rate constant on temperature is best described by
Not quite — the answer is C.
The Arrhenius equation quantitatively describes how k varies exponentially with temperature: k = Ae^(−Ea/RT). Collision theory explains why collisions must exceed threshold energy but does not give the exponential mathematical form. Transition state theory complements but does not replace Arrhenius.
Q11Rate Law and Rate Constant
Rate law expresses the rate of a reaction in terms of which of the following?
Not quite — the answer is A.
Rate law is an experimentally determined expression relating rate to concentration of reactants raised to observed powers. Temperature affects k (the rate constant), not the rate law expression itself. Pressure and time are not part of rate law.
Q12Rate Law and Rate Constant
For the reaction A + B → products, the experimentally determined rate law is rate = k[A][B]². Which statement about this rate law is correct?
Not quite — the answer is A.
Rate law exponents are determined experimentally, not from stoichiometry. Here order w.r.t. A = 1, w.r.t. B = 2, overall = 3. Option C is the classic NEET trap — exponents equal stoichiometric coefficients only in elementary reactions.
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Get RankUp on Google PlayQ13Order of Reaction
For a zero order reaction A → products, the integrated rate law is
Not quite — the answer is A.
Zero order integrated law: [A] = [A]₀ − kt (linear decrease in concentration with time). Option B is first order, Option C is second order — both are NEET-standard traps. The zero order law is the only one where concentration itself (not its log or reciprocal) is linear with time.
Q14Order of Reaction
The following data is given for reaction A → products: t=0 min, [A]=1.0 M; t=10 min, [A]=0.5 M; t=20 min, [A]=0.25 M; t=30 min, [A]=0.125 M. The order of reaction is
Not quite — the answer is B.
The half-life is constant at 10 min regardless of concentration — this is the hallmark of first order kinetics. For zero order, half-life would decrease. For second order, half-life would increase. Constant half-life = first order.
Q15Molecularity of Reaction
Molecularity of a reaction is defined as the number of
Not quite — the answer is A.
Molecularity counts the number of molecules, atoms, or ions colliding in a single elementary step. It is a property of the mechanism, not the stoichiometric equation. Option D (balanced equation) describes stoichiometry, not molecularity.
Q16Molecularity of Reaction
Which of the following values can molecularity of a reaction NEVER have?
Not quite — the answer is C.
Molecularity is always a positive integer (1, 2, or 3) because it counts discrete colliding species. Fractional values are impossible — you cannot have half a collision event. Order, not molecularity, can be fractional (e.g., 0.5 for certain chain reactions).
Q17Half Life of Reactions
Half-life of a reaction is defined as the time required for the reactant concentration to become
Not quite — the answer is A.
Half-life (t½) is the time for [A] to fall to [A]₀/2. One-third and one-fourth correspond to other fractional lives, not half-life. Zero would be complete reaction, not half-life.
Q18Half Life of Reactions
The half-life of a zero-order reaction depends on
Not quite — the answer is B.
For zero-order, t½ = [A]₀/2k; it directly depends on initial concentration. Option A is a trap — k is in the denominator but [A]₀ in the numerator makes concentration the defining variable. Option C affects k indirectly but is not what t½ directly depends on.
Q19Arrhenius Equation and Activation Energy
Which of the following correctly represents the Arrhenius equation?
Not quite — the answer is A.
The Arrhenius equation is k = Ae^(−Ea/RT); the negative sign in the exponent is critical. Option B with a positive exponent would imply k decreases with Ea, reversing physical meaning. Option C omits R, making it dimensionally incorrect.
Q20Arrhenius Equation and Activation Energy
Activation energy (Ea) is best defined as the minimum energy that reactant molecules must possess to
Not quite — the answer is B.
Ea is the energy difference between reactants and the transition state (activated complex). Option A is wrong — products may or may not be stable; Ea is about the energy barrier, not product stability. Option C describes physical processes, not chemical activation.
Q21Integrated Rate Equations
The integrated rate equation is used to relate which two quantities of a reaction?
Not quite — the answer is A.
The integrated rate law is obtained by integrating the differential rate law — it expresses how concentration of reactant changes with time. Temperature affects k (via Arrhenius), but that is a separate relationship. Options C and D describe Arrhenius and gas law relationships respectively.
Q22Integrated Rate Equations
For a zero-order reaction, the integrated rate equation is
Not quite — the answer is B.
Zero-order rate law: −d[A]/dt = k. Integrating gives [A]t = [A]₀ − kt — a linear decrease. Option A is the first-order integrated form; option C is second-order; option D is the exponential form of first-order decay.
Q23Rate of Reaction
Instantaneous rate of a reaction is mathematically expressed as
Not quite — the answer is C.
Instantaneous rate = dx/dt, the limiting value of Δx/Δt as Δt approaches zero — i.e., the slope of the tangent to the concentration–time curve. Option D uses Δt→∞ which gives zero, not instantaneous rate.
Q24Rate of Reaction
Which of the following is the correct SI unit of rate of reaction?
Not quite — the answer is D.
Rate = change in concentration / time = mol L⁻¹ / s = mol L⁻¹ s⁻¹. Option B (mol s⁻¹) omits the volume term. Option C (mol L⁻¹) omits the time term. Option A is amount, not rate.
ELITE question · AIR under 50 level
This chapter has 222 ELITE questions for students aiming at the very top. They are only in the app.
Unlock ELITE questions in the appKey Kinetics Formulas
Quick revision: most questions in this chapter test these facts.
| Concept | Key Formula / Fact |
|---|---|
| Rate law | Rate = k[A]^m[B]^n; order = m + n; determined experimentally, not from stoichiometry |
| Zero order | k = [A₀ − A]/t; t½ = [A₀]/2k; [A] vs t is linear |
| First order | k = (2.303/t)log([A₀]/[A]); t½ = 0.693/k; independent of [A₀] |
| Arrhenius equation | k = Ae^(−Ea/RT); log(k₂/k₁) = (Ea/2.303R)(1/T₁ − 1/T₂) |
| Activation energy | Minimum energy needed for reaction; catalyst lowers Ea without being consumed |
| Molecularity | Number of molecules in elementary step; always whole number (1, 2 or 3) |
What the app covers in this chapter
552 questions in total, each with a detailed explanation.
| Important PYQ Mixed Concepts | 100 |
| Mixed Revision | 77 |
| Grand Test | 60 |
| Rate of Reaction | 40 |
| Factors Affecting Rate of Reaction | 40 |
| Rate Law and Rate Constant | 40 |
| Order of Reaction | 40 |
| Molecularity of Reaction | 40 |
| Half Life of Reactions | 39 |
| Arrhenius Equation and Activation Energy | 39 |
| Integrated Rate Equations | 37 |
Questions students ask
Is Chemical Kinetics important for NEET?
Yes — first-order kinetics, half-life and Arrhenius equation are tested every year. Both conceptual and numerical questions appear.
Which topics should I revise first?
Master zero and first-order integrated rate equations, half-life formulas, Arrhenius equation for temperature dependence, and the distinction between order (experimental) and molecularity (theoretical).
How many questions from this chapter are on RankUp?
The RankUp app has 552 questions on Chemical Kinetics, including 222 ELITE questions. Every question has a detailed explanation.
