75 free MCQs on Chemical Kinetics, each with its own worked answer and explanation. Study the speed of reactions and what affects it: concentration, temperature, and catalysts. Covers rate law, order of reaction, the Arrhenius equation, and reaction mechanisms step by step.
Take the timed Chemical Kinetics chapterwise test →75 practice questions on Chemical Kinetics, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Chemical Kinetics notes.
First-order decay curve: concentration halves every t½, and that half-life is constant - a defining test for first-order kinetics.
Q1.
For the reaction N<sub>2</sub> + 3H<sub>2</sub> -> 2NH<sub>3</sub>, the rate of disappearance of H<sub>2</sub> is how many times the rate of disappearance of N<sub>2</sub>?
Q2.
The instantaneous rate of a reaction is obtained from a concentration-time graph by taking the:
Q3.
The rate constant of a reaction depends on which of the following?
Q4.
For an elementary reaction, the order of reaction is equal to:
Q5.
The average rate of a reaction over a time interval is calculated as the:
Q6.
Reaction rate is measured as:
Q7.
Increasing temperature generally:
Q8.
A catalyst increases reaction rate by:
Q9.
The order of a reaction is:
Q10.
For a first-order reaction, the unit of rate constant k is:
Q11.
The minimum energy required for a reaction to occur is called:
Q12.
The half-life of a first-order reaction:
Q13.
For a zero-order reaction, the rate is:
Q14.
The rate law for a reaction must be determined by:
Q15.
Which factor does NOT change the equilibrium constant K of a reaction?
Q16.
The branch of chemistry that deals with the rates of reactions is:
Q17.
The rate of a reaction is the change in concentration of a reactant or product per unit:
Q18.
The minimum energy that colliding molecules must possess in order to react is the:
Q19.
Raising the temperature generally causes the rate of a reaction to:
Q20.
A substance that increases a reaction rate while itself remaining unchanged at the end is a:
Q21.
The usual units for the rate of a reaction are:
Q22.
For a first-order reaction, the half-life is ___ the initial concentration:
Q23.
The sum of the powers of the concentration terms in the experimental rate law is the:
Q24.
Which of these does NOT normally affect the rate of a reaction?
Q25.
A reaction whose rate is independent of the concentration of the reactant is of:
Q26.
In collision theory, the fraction of molecules possessing energy equal to or greater than the activation energy is represented by the term:
Q27.
The threshold energy of a reaction equals the activation energy plus the:
Q28.
For a zero-order reaction, a graph of concentration of reactant against time is a:
Q29.
For a first-order reaction, a plot of log[A] against time is a straight line whose slope equals:
Q30.
If the activation energy of a reaction were zero, its rate constant on raising the temperature would:
Q31.
The Arrhenius equation k = Ae<sup>-Ea/RT</sup> shows that k:
Q32.
For rate = k[A][B], if [A] doubles and [B] is halved, the rate:
Q33.
The half-life of a first-order reaction with k = 0.1 min⁻¹ is:
Q34.
For a second-order reaction, the unit of rate constant k is:
Q35.
The molecularity of the elementary reaction 2NO + O₂ → 2NO₂ is:
Q36.
A catalyst changes all of these EXCEPT:
Q37.
In a pseudo-first-order reaction, one reactant is present in:
Q38.
Activation energy can be calculated from the slope of the graph of:
Q39.
A reaction is found to be of zero order with respect to a reactant. What does this indicate about the rate of the reaction?
Q40.
For a reaction with rate = k[A]<sup>2</sup>[B], what happens to the rate if the concentration of both A and B are doubled?
Q41.
The rate constant of a zero-order reaction has units of:
Q42.
The rate constant of a first-order reaction has units of:
Q43.
For a first-order reaction, the half-life t½ in terms of the rate constant k is:
Q44.
The number of reacting species taking part in an elementary reaction step is its:
Q45.
According to the Arrhenius equation k = A e<sup>−Ea/RT</sup>, increasing the activation energy Ea:
Q46.
A plot of ln k against 1/T (the Arrhenius plot) is a straight line with slope:
Q47.
As a typical reaction proceeds with time, its rate generally:
Q48.
For the first-order reaction 2N₂O₅ → 4NO₂ + O₂, doubling the concentration of N₂O₅ changes the rate by a factor of:
Q49.
The temperature coefficient of a reaction is the factor by which its rate increases for every rise of:
Q50.
A catalyst increases the reaction rate by providing a pathway of:
Q51.
The rate of a reaction increases by a factor of about 2.83 (2 times root 2) when the reactant concentration is doubled. The order with respect to that reactant is:
Q52.
For a first-order reaction, the time taken for 99.9% completion is approximately how many half-lives?
Q53.
For the reaction 2A -> products with rate = k[A], the rate is 2 x 10<sup>-3</sup> M/s when [A] = 0.5 M. The rate constant k is:
Q54.
In a first-order reaction, the fraction of the reactant left after three half-lives is:
Q55.
The temperature coefficient of a reaction is 2. If the temperature is raised by 30 degrees Celsius, the rate of reaction becomes about:
Q56.
A first-order reaction has k = 0.231 min⁻¹. The time for 90% completion is:
Q57.
The integrated rate law for a second-order reaction (rate = k[A]²) is:
Q58.
Concentration of A falls from 0.4 M to 0.2 M in 20 min, and from 0.2 M to 0.1 M in another 20 min. The order is:
Q59.
A catalyst lowers activation energy without changing:
Q60.
The pre-exponential factor A in the Arrhenius equation represents:
Q61.
For a zero-order reaction A → B with [A]₀ = 0.5 M and k = 0.05 M/s, total reaction time is:
Q62.
For a reaction with k₁ = 0.005 s⁻¹ at 300 K and k₂ = 0.020 s⁻¹ at 320 K, the activation energy is approximately:
Q63.
For a reaction, a graph of log(rate) vs log[A] gives a straight line with slope 2. The order with respect to A is:
Q64.
A reaction has a rate constant of 4 x 10<sup>-3</sup> s<sup>-1</sup> at 300 K and 1.6 x 10<sup>-2</sup> s<sup>-1</sup> at 340 K. Using the Arrhenius equation, the activation energy is closest to which value (R = 8.314 J/K/mol)?
Q65.
For a first-order reaction, a graph of ln[A] versus time gives a straight line. If the line has a slope of -0.0231 min<sup>-1</sup>, what is the half-life of the reaction?
Q66.
For a first-order reaction, the time needed for 75% completion is ___ the half-life:
Q67.
The half-life of a zero-order reaction is given by:
Q68.
The rate of a reaction doubles when the temperature rises from 300 K to 310 K. Its temperature coefficient is about:
Q69.
For a reaction with the rate law rate = k[A][B]², the overall order is:
Q70.
In the Arrhenius equation k = A e<sup>−Ea/RT</sup>, the term A is called the:
Q71.
A first-order reaction has a rate constant k = 0.0693 min⁻¹. Its half-life is:
Q72.
The molecularity of a reaction can never be:
Q73.
For a reaction A → products, doubling [A] quadruples the rate. The order with respect to A is:
Q74.
The activation energy of a catalysed reaction, compared with the uncatalysed reaction, is:
Q75.
The integrated rate equation [A] = [A₀] − kt describes a reaction of:
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