Chemical Kinetics Additional Practice Test

12th Standard Chemistry — Chemical Kinetics: Additional Online Practice Test

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Which of the following units is used to express the rate of a gas phase reaction when the concentration of species is expressed in terms of partial pressure?

A.mol L\(^{-1}\) s\(^{-1}\) B.atm s\(^{-1}\) C.mol s\(^{-1}\) D.atm mol\(^{-1}\) s\(^{-1}\)

For a general reaction \(x A + y B \to l C + m D\), what is the correct relationship between the rates of change of concentration for the different species?

A.Rate = \(-x \frac{d[A]}{dt} = -y \frac{d[B]}{dt}\) B.Rate = \(-\frac{1}{x} \frac{d[A]}{dt} = \frac{1}{l} \frac{d[C]}{dt}\) C.Rate = \(\frac{1}{y} \frac{d[B]}{dt} = \frac{1}{m} \frac{d[D]}{dt}\) D.Rate = \(-x \frac{d[A]}{dt} = l \frac{d[C]}{dt}\)

How is the instantaneous rate of a chemical reaction at a particular time 't' determined from a experimental concentration vs. time curve?

A.By calculating the total change in concentration over the total time. B.By finding the area under the curve between zero and time t. C.By calculating the slope of the tangent drawn to the curve at time t. D.By taking the reciprocal of the reactant concentration at time t.

Which of the following characteristics correctly describes the rate constant 'k' of a reaction?

A.It depends on the initial concentration of the reactants. B.It is equal to the rate of reaction when the concentration of each reactant is unity. C.Its value remains constant even if the temperature changes. D.It represents the speed at a specific instant during the reaction.

Which property distinguishes molecularity from the order of a reaction?

A.Molecularity can be zero or fractional. B.Order is always a whole number and cannot be zero. C.Molecularity is always a whole number and cannot be zero or fractional. D.Order is assigned for each individual elementary step.

What is the order of the reaction for the decomposition of dinitrogen pentoxide (\(N_2O_5\))?

A.Zero order B.First order C.Second order D.Third order

Which condition allows a higher-order reaction to be studied as a pseudo-first order reaction?

A.Carrying out the reaction at a very high pressure. B.Taking one of the reactants in large excess. C.Using a heterogeneous catalyst. D.Decreasing the temperature to near absolute zero.

For a zero-order reaction, a plot of reactant concentration \([A]\) versus time yields a straight line. What does the slope of this line represent?

A.The rate constant \(k\) B.The negative rate constant \(-k\) C.The initial concentration \([A]_0\) D.The natural logarithm of the rate constant \(\\ln k\)

How does the half-life (\(t_{1/2}\)) of a first-order reaction change if the initial concentration of the reactant is doubled?

A.The half-life also doubles. B.The half-life is reduced by half. C.The half-life remains unchanged. D.The half-life increases by a factor of four.

Q10

Which of the following is true for the half-life of a zero-order reaction?

A.It is independent of the initial concentration. B.It is inversely proportional to the initial concentration. C.It is directly proportional to the initial concentration. D.It is inversely proportional to the square of the initial concentration.

Q11

According to collision theory, even if molecules collide with sufficient energy, they may not react. What additional factor is necessary for an effective collision?

A.High pressure B.Presence of an inert gas C.Proper orientation of colliding molecules D.Small molecular size

Q12

In the Arrhenius equation \(k = A e^{-E_a/RT}\), what does the term 'A' represent?

A.Activation energy B.Frequency factor C.Gas constant D.Reaction rate

Q13

When plotting \(\\ln k\) versus \(1/T\) based on the Arrhenius equation, a straight line is obtained. What is the slope of this line?

A.\(\\ln A\) B.\(-E_a / R\) C.\(E_a / 2.303 R\) D.\(R / E_a\)

Q14

How does a catalyst affect the rate of a chemical reaction?

A.It increases the rate by increasing the enthalpy of the reaction. B.It decreases the rate by increasing the activation energy. C.It increases the rate by providing an alternative path with lower activation energy. D.It has no effect on the reaction rate.

Q15

In the reaction between marble chips (\(CaCO_3\)) and hydrochloric acid, why does powdered marble react faster than larger chips of the same mass?

A.The powder has a higher temperature. B.The powder has a larger surface area available for collisions. C.The powder acts as a catalyst for the reaction. D.The powder decreases the activation energy of the reaction.

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About this Chemical Kinetics test

This free online practice test covers Chemical Kinetics from the 12th Standard Chemistry (Samacheer Kalvi) syllabus. Choose the number of questions and an optional time limit, then answer and submit — everything is checked in your browser, with the correct answers and a worked explanation shown at the end. For the full solutions to every question in this set, see the solved MCQs page.

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