CBSE Questions for Class 12 Engineering Chemistry Chemical Kinetics Quiz 2 - MCQExams.com

For a given reaction which one is higher than the rest among the following?
  • Average energy
  • Threshold energy
  • activation energy
  • Normal energy
The energy to be possessed by the molecule participating in the reaction to give the products is:
  • < activation energy
  • threshold energy
  • < average energy
  • threshold energy + average energy
Which of the following is not a first order reaction?
  • Decomposition of $$H_{2}O_{2}$$
  • Decomposition of $$N_{2}O_{5}$$
  • Decomposition of $$N_{2}O$$
  • Decomposition of $$SO_{2}Cl_{2}$$
The reaction $$L\rightarrow M$$ is started with $$10.0\ gm$$ of $$L$$. After $$30$$ and $$90$$ minutes, $$5.0\ gm$$ and $$1.25\ gm$$ of $$L$$ respectively are left. The order of the reaction is:
  • 0
  • 1
  • 2
  • 3
A substance having initial concentration (a) reacts according to zero order kinetics. How much time will the reaction take to reach the completion?
  • $$\dfrac{a}{K}$$
  • $$\dfrac{K}{a}$$
  • $$\dfrac{a}{2K}$$
  • $$\dfrac{2K}{a}$$
At 400K, the half-life of a sample of a gaseous compound initially at 56.0 $$kPa$$ is 340s. When the pressure is 28.0 $$kPa$$, the half-life is 170s. The order of the reaction is:
  • 0
  • 2
  • 1
  • 1/2
$$N_{2}O_{2} (g)\rightarrow2NO$$   is  a first-order reaction interms of the concentration of $$N_{2}O_{2} (g)$$  .Which of the following is valid, $$[N_{2}O_{2} ]$$  being constant?
  • $$[NO]=[N_{2}O_{2}]_{0}e^{-kt}$$
  • $$[NO]=[N_{2}O_{2}]_{0}(1-e^{kt})$$
  • $$[NO]=[N_{2}O_{2}]_{0}(e^{-kt}-1)$$
  • $$[NO]=[N_{2}O_{2}]_{0}(1-e^{-kt})$$
From the graph, pick out the correct one :

11598.JPG
  • $$E*$$ for the forward reaction is $$E_{A}-E_{B} $$
  • $$E*$$ for the backward reaction is $$E_{C}-E_{A} $$
  • $$E*$$ for reverse reaction is $$\,> \,E*$$         for forward reaction
  • $$E*$$ for forward reaction $$\,>\,E*$$          for backward reaction
For a first order reaction, the half-life period is:
  • inversely related to initial concentration
  • directly related to initial concentration
  • independent of initial concentration
  • inversely related to the square of initial concentration
For a first order reaction, the half life is equal to:
  • 0.693 x k
  • 0.693/k
  • k/0.693
  • $$\dfrac{2.303}{k}$$
If the initial concentration is reduced to 1/4th in a zero order reaction, then the time taken for half the reaction to complete:
  • remains same
  • becomes 4 times
  • becomes one-fourth
  • doubles
The amount left after completion of average life period in a first order reaction is :
  • $$\dfrac{a(e-1)}{e+1}$$
  • $$\dfrac{a}{e-1}$$
  • $$\dfrac{a(e-1)}{e}$$
  • $$\dfrac{a}{e}$$
For the reaction A $$\rightarrow $$ B it has been found that the order of the reaction is zero with respect to A. Which of the following expressions correctly describes the reaction?
  • $$K=\dfrac{2.303}{t}log\dfrac{[A_{0}]}{[A]}$$
  • $$[A_{0}] - [A] = Kt$$
  • $$t_{1/2}=\dfrac{0.693}{K}$$
  • $$t_{1/2}\propto \dfrac{1}{[A_{0}]}$$
The following figure denotes the energy diagram for a reaction.
Then the activation energy for the reverse reaction is:
11611.jpg
  • 2x
  • 2y
  • x+ y
  • y-x
$$SO_{2}Cl_{2} \rightarrow  SO_{2}+Cl_{2}$$ is a first order gas reaction with $$k=2.2\times 10^{-5}\sec^{-1}$$ at $$320^o C$$. The percentage of $$SO_{2}Cl_{2}$$ decomposed on heating for 90 minutes is:
  • 1.118
  • 0.1118
  • 18.11
  • 11.18
Which equation represents the time to complete 90% of first order reaction?
  • $$\dfrac{k}{2.303}log(\frac{4}{3})$$
  • $$\dfrac{2.303}{k}log(\frac{3}{4})$$
  • $$\dfrac{2.303}{k}$$
  • $$\dfrac{2.303}{k}log(3)$$
$$A_{(g)}  \rightarrow  B_{(g)}$$ is a first order reaction. The initial concentration of A is 0.2mol $$l^{-1}$$ . After 10 minutes, the concentration of B is found to be 0.18mol $$l^{-1}$$ . Calculate rate constant of the reaction?
  • 0.2303
  • 2.303
  • 0.693
  • 0.01
At room temperature the reaction between NO and $$O_{2}$$ to give $$NO_{2}$$ is fast while that of between CO and $$O_{2}$$ is slow. It is because:
  • CO is smaller in size than that of NO
  • CO is poisonous
  • the activation energy for the reaction 2NO+$$O_{2}$$ $$\rightarrow $$ 2$$NO_{2}$$ is less than 2CO+$$O_{2}$$ $$\rightarrow $$ 2$$CO_{2}$$
  • the activation energy for the reaction 2CO+$$O_{2}$$ $$\rightarrow $$ 2$$CO_{2}$$ is less than 2NO+$$O_{2}$$ $$\rightarrow $$ 2$$NO_{2}$$
The concentration of reaction decreases from 0.2M to 0.05M in 5 minutes. The rate of reaction in $$mol. lit^{-1}.s^{-1}$$ is:
  • $$8.3 \times 10^{-4}$$
  • $$0.05$$
  • $$0.0005$$
  • $$0.15$$
A first order reaction was commenced with 0.2 M solution of the reactants. If the molarity of the solution falls to $$0.02M$$ after 100 minutes the rate constant of the reaction is:
  • $$2\times 10^{-2}min^{-1}$$
  • $$2.3\times 10^{-2}min^{-1}$$
  • $$4.6\times 10^{-2}min^{-1}$$
  • $$2.3\times 10^{-1}min^{-1}$$
After how many seconds will the concentration of the reactant in a first order reaction be halved, if the rate constant is 1.155x10$$^{-3} sec^{-1}$$?
  • 600
  • 100
  • 60
  • 10
With respect to the figure which of the following statement is correct?
11614_f523de8eca9b4f0a9f4c9ccbeec4f3e6.png
  • $$E_{A}$$ for forward reaction is $$E_{A}-E_{B} $$
  • $$E_{A}$$ for forward reaction is $$E_{C}-E_{A} $$
  • $$E_{A}$$ for reverse reaction is greater than $$E_{A}$$for forward reaction
  • $$E_{A}$$ for forward reaction is greater than $$E_{A}$$for backward reaction
For a first order reaction $$t_{0.75}$$ is 1368 seconds.Therefore, the specific rate constant in $$sec^{-1}$$ is:
  • $$10^{-3}$$
  • $$10^{-2}$$
  • $$10^{-9}$$
  • $$10^{-5}$$
A first-order reaction is carried out with an initial concentration of $$10$$ mole per litre and $$80$$% of the reactant changes into the product. Now if the same reaction is carried out with an initial concentration of $$5$$ mol per litre, the percentage of the reactant changing to the product is:
  • $$40$$
  • $$80$$
  • $$160$$
  • $$\text{cannot be calculated}$$
Statement - I : The reactions $$2NO+O_{2}\rightarrow 2NO_{2}$$ and $$2CO+O_{2}\rightarrow 2CO_{2}$$ proceed at the same rate because they are similar.
Statement - II Above two reactions will have different activation energies.
  • Both statements are true Statement - II is correct explantion of Statement - I
  • Both statements are true but Statement -II is not correct explantion of Statement - I
  • Statement - I is true but Statement - II is false.
  • Statement - I is false but Statement - II is true.
The most common molecular collisions are in between:
  • 2 molecules
  • 3 molecules
  • 4 molecules
  • 5 molecules
The half life of first order reaction $$PCl_{5} \rightarrow PCl_{3}+Cl_{2}$$ is 10 minutes at a certain temperature. The time in which the concentration of $$PCl_{5}$$ would be reduced to 10% of the initial concentration is:
  • 26 min
  • 33 min
  • 71 min
  • 90 min
The rate constant of a first order reaction is $$0.0693$$ $$min^{-1}$$. 
Time (in minutes) required for reducing an initial concentration of $$20mol$$ $$lit^{-1}$$ to $$2.5mol$$ $$lit^{-1}$$ is :
  • $$40$$
  • $$30$$
  • $$20$$
  • $$10$$
For the gas phase decomposition $$A\rightarrow2B$$, the rate constant is $$6.93\times 10^{-3}$$ $$min^{-1}$$ at 300K. The percentage of A remaining at the end of 300 minutes is :
  • 75
  • 50
  • 25
  • 12.5
From the graph pick out the correct one:

11924_eae4babad3dc43a7aa20bee76c948733.png
  • $$\Delta E$$ for forward reaction is $$B-A$$
  • $$\Delta E$$ for the forward reaction $$C-A$$
  • $$\Delta E$$ reverse is greater than forward
  • $$\Delta E$$ for forward reaction is $$A + B$$
The rate of a certain reaction at different times are as follows:
Timerate ($$mole$$ $$lit^{-1}\sec^{-1}$$)
I) 0a) $$2.8 \times 10^{-2}$$
II) 10b) $$2.78\times 10^{-2}$$
III) 20c) $$2.81\times 10^{-2}$$
IV) 30d) $$2.79\times 10^{-2}$$
The correct matching is:
  • zero order
  • first order
  • second order
  • third order
For a zero-order reaction $$A$$ $$\rightarrow $$ product, the rate constant is $$10^{-2}\ mol\ L^{-1}\ s^{-1}$$ . Starting with 10 moles of $$A$$ in a 1 L vessel, how many moles of $$A$$ would be left unreacted after 10 minutes?
  • 5 moles
  • 6 moles
  • 4 moles
  • 10 moles
Which is the graphical representation for the zeroth order reaction?
An activation energy of the forward reaction is same as activation energy of the backward reaction.
  • True
  • False
The temperature dependence of rate constant (k) of a chemical reaction is written in terms of Arrhenius equation, $$k = A.e^{E^{\ast }/RT}. Activation energy $$(E^{\ast })$$ of the reaction can be calculated by plotting
  • K vs T
  • K vs $$\frac{1}{log T}$$
  • log K vs $$\frac{1}{T}$$
  • log k vs $$\frac{1}{log T}$$
Identify the false statements among the following:
  • Rate of reaction is directly proportional to activation energy
  • Order of a reaction can be determined by experimental method only
  • Rate law never coincides with the stoichiometry of the reaction
  • Order of reaction cort different reactants may be different.

What is the hybridisation in $$AsF_4^-$$ ion :
  • sp
  • $$sp^2$$
  • $$sp^3$$
  • $$sp^3 d$$
Half life period of $$C^{14}$$ in years is:
  • $$500$$
  • $$5000$$
  • $$50$$
  • $$5\times 10^4$$
Increase in temperature increases the activation energy.

State whether the given statement is true or false.
  • True
  • False
For an endothermic reaction, energy of activation is E$$_{a}$$ and enthalpy of reaction is H (both of these in kJ/mol). Minimum value of E$$_{a}$$ will be:
  • less than H
  • equal to H
  • more than H
  • equal to zero
The rate of reaction is directly proportional to the activation energy.
  • True
  • False
Statement 1:
In a zero order reaction, if the concentration of the reactant is doubled, the half-life period is also doubled.
Statement 2:
For a zero-order reaction, the rate of the reaction is independent of initial concentration.
  • Statement 1 is True, statement 2 is True, statement 2 is a correct explanation of statement 1.
  • Statement 1 is True, statement 2 is True, statement 2 is not a correct explanation of statement 1.
  • Statement 1 is true, Statement 2 is False.
  • Statement 1 is False, Statement 2 is True.
The activation energy of the forward reaction and backward reaction decreases by $$30 kcal$$ then which of the following statement is correct?
  • $$\Delta H$$ will remain constant.
  • $$\Delta H$$ will decrease.
  • $$\Delta H$$ will increase.
  • The reaction will be exothermic.
What are effective collisions?
  • Collisions leading to the transformation of reactants to products
  • formation of activated complex
  • collison between two reactant to decrease the activation energy
  • collison between two reactant to overcome activation energy barrier
Which of the following is/are correct statement?
  • Stoichiometry of a reaction tells about the order of the elementary reactions
  • For a zero order reaction, rate and the rate constant are identical
  • A zero order reaction is controlled by the factors other than concentration of reactants
  • A zero order reaction is always an elementary reaction
The initial rate of zero-order reaction of the gaseous reaction $$A(g)\rightarrow2B(g)$$ is $$10^{-2}M min^{-1}$$. If the initial concentration of A is 0.1 M, then the concentration of B after 60 sec would be:
  • 0.09 M
  • 0.01 M
  • 0.02 M
  • 0.002 M
Statement: The rate of instantaneous reactions can be determined experimentally.

State whether the given statement is true or false.
  • True
  • False
In a chemical reaction, two reactants take part. The rate of reaction is directly proportional to the concentration of one of them and inversely proportional to the concentration of the other. The order of reaction is:
  • 0
  • 1
  • 2
  • 4
In the following reaction, $$ A\rightarrow B$$, rate constant is $$1.2\times10^{-2} Ms^{-1}$$. What is the concentration of $$B$$ after $$10$$ min, if we start with $$10\ M$$ of $$A$$?
  • 7.2 M
  • 4.5 M
  • 6.7 M
  • 7.0 M
For the first-order reaction $$A\rightarrow product$$s, the half-life is $$200$$s. The rate constant of the reaction is:
  • $$3.46\times 10^{-2} s^{-1}$$
  • $$3.46\times 10^{-3} s^{-1}$$
  • $$3.46\times 10^{-4} s^{-1}$$
  • $$3.75\times 10^{-5} s^{-1}$$
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