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Test: Energy Of Activation


22 Questions MCQ Test Chemistry Class 12 | Test: Energy Of Activation


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This mock test of Test: Energy Of Activation for Class 12 helps you for every Class 12 entrance exam. This contains 22 Multiple Choice Questions for Class 12 Test: Energy Of Activation (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Energy Of Activation quiz give you a good mix of easy questions and tough questions. Class 12 students definitely take this Test: Energy Of Activation exercise for a better result in the exam. You can find other Test: Energy Of Activation extra questions, long questions & short questions for Class 12 on EduRev as well by searching above.
QUESTION: 1

Direction (Q. Nos. 1-12) This section contains 12 multiple choice questions. Each question has four choices (a), (b), (c) and (cl), out of which ONLY ONE is correct.

Q.

The rate of a reaction doubles when its temperature changes from 300 K to 310 K. Activation energy of such a reaction will be (Given, R = 8.314 J K-1 mol-1, log2 = 0.3010).

Solution:


QUESTION: 2

In the following reaction

N2O  N2+O

k = (5.0 x 1011 L mol-1 s-1) e -29000R/T, Ea (energy o f activation) is 

Solution:

By Arrhenius equation


QUESTION: 3

Rate of a reaction can be expressed by Arrhenius equation as k = Ae-EalRT. In this equation, Ea represents.

Solution:


Ea (activation energy) is the energy required to activate the reactant so that they may collide and give the final product. Below point B, the reactants will not react at all.

QUESTION: 4

In the upper atmosphere, form ation of H2O2 takes place as

H2O+O → 2OH → H202

ΔH0 = 72.0 Kj mol-1 ; Ea = 77.0 kJ mol-1

Ea for the bim olecular recombination of two OH radicals to form H2O and O is
Solution:



QUESTION: 5

How much rate is affected in the presence of catalyst at 300 K?
Solution:

k1 (no catalyst) = Ae -Ea/RT 
∴
∴ 

Thus, rate is affected (28.03) times.
k1 (no catalyst) = Ae-Ea/RT
k2 (with catalyst) = Ae-(Ea - 2)/RT 

QUESTION: 6

For a reaction,

A → Product

t50  = 100 min at temprature T1

and t50 = 80 min at temprature T2

Thus, 
Solution:

On increasing temperature, number of collisions hence kinetic energy increases.

Thus, 


Thus rate of the reaction or rate constant increases with increase in temperature.
Half-life of any reaction
Thus, half-life decreases with increase in temperature, reaction may be exothermic or endothermic.
Thus,   

QUESTION: 7

Rate constant (k) of a reaction has least value at
Solution:

k varies with temperature as given by Arrhenius equation
 

k has least value at low 7 and high Ea.

QUESTION: 8

Two reactions with different activation energies have the same rate at room temperature. Which statement correctly describes the rates of these two reactions at the same higher temperature?
Solution:



If temperature is increased to T`,

If 
Thus, reaction with smaller activation energy will be faster on increasing temperature.

QUESTION: 9

The activation energy of the reaction at a given temperature is found to (2.303 RT) J mol-1. The ratio of rate constant to the Arrhenius factor is
Solution:





QUESTION: 10

From the given figure, select the correct statement about activation energy.

Activation energy of
Solution:

Energy required to take the reactant to the activated state is (E1 + E2). Since, reactions is endothermic, product is less stable.

QUESTION: 11

The rate of a chemical reaction doubles for every 10°C rise of temperature. If the tem perature is raised by 50°C, the rate of the reaction increases by about

[AIEEE 2011]
Solution:

Number of ten degrees in 
Increase in rate due to 10° rise in temperature = 2
Increase in rate due to 50° rise in temperature = 25 = 32 times

QUESTION: 12

A reactant A forms two products B and C as given

A  B, Activation energy Ea1

A  C, Activation energy Ea2

if Ea2 = 2Ea1, then k1 and K2 are related as 

[AIEEE 2011]
Solution:






∴ 

QUESTION: 13

Direction (Q. No. 14) Choices for the correct combination of elements from Column I and Column II are given as options (a), (b), (c) and (d), out of which one is correct.

  Rate constant {k) of a reaction is given by

Match the given property in Column I with its related value in Column II and select answer from codes given:
Solution:

By Arrhenius equation, 

∴  
Thus, (i)→(r)

Unit of k is in min-1.

Thus, (ii)→(p)
At 500 K, 
k = 10 min-1

∴ 
10 min-1 (0.2M) = 2 M min-1
Thus (iii)→(q)


Thus, (iv)→(s)

QUESTION: 14

Direction (Q. Nos. 15-18)This section contains 2 paragraphs, which describing theory, experiments, data, etc. Four questions related to the paragraphs have been given. Each question has only one correct answer among the four given options (a), (b), (c) and (d).

Passage I

For the displacement reaction,

[Co(NH3)5Cl]2+ (aq) + H2O (l) → [Co(NH3)5H2O]3+ + Cl- (aq)

The rate constant is given by

Q. 

Rate constant at 25°C is 
Solution:






QUESTION: 15

Passage I

For the displacement reaction,

[Co(NH3)5Cl]2+ (aq) + H2O (l) → [Co(NH3)5H2O]3+ + Cl- (aq)

The rate constant is given by

Q. 

Energy of activation for this reaction is
Solution:


At 298 K, log k (min-1)




QUESTION: 16

Passage II

For the opposing reaction,

Ea (forward reaction) = 100 kJ mol-1

Pre-exponential factor A = 1.0 x 1010 M-1s-1

Q. 

The value of k1 and k2 at 700K respectively are
Solution:




Also,

=345 M-1s-1




∴ 
 

QUESTION: 17

Passage II

For the opposing reaction,

Ea (forward reaction) = 100 kJ mol-1

Pre-exponential factor A = 1.0 x 1010 M-1s-1

Q. 

The rate constant (k1) for the forward reaction at 1000 K is
Solution:




Also,
 
345 m-1s-1




∴ 
 

*Answer can only contain numeric values
QUESTION: 18

Direction (Q. Nos. 19-21) This section contains 3 questions. When worked out will result in one integer from 0 to 9 (both inclusive).

At room temperature (27°C) milk turns sour in about 64 h. In a refrigerator at -3°C, milk can be stored x times as long before it sours. The activation energy of the reaction that causes the souring of milk is 11.231 kcal mol-1.
What is the value of x?

Solution:

Rate of souring of milk at 27°C (300 K) is  times faster than at-3°C(270K).
∴ 
∴ 
11.231 kcal mol-1 = 2.303 x 2 x10-3 kcal mol-1k-1

*Answer can only contain numeric values
QUESTION: 19

The Arrhenius equations for the rate constant of decomposition of methyi nitrite and ethyl nitrite are


Find the temperature (in °C), at which rate contants are equal.

Solution:

Both are first order reactions (unit of k beings-1)





∴
 
 

*Answer can only contain numeric values
QUESTION: 20

For the following sequence of reactions

Thus, observed Ea is .....kJ mol-1.

Solution:





∴ 

*Multiple options can be correct
QUESTION: 21

This section contains 2 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONE or MORE THAN ONE are correct.

Select the correct statement(s) about collision theory of reaction rates.
Solution:

All the given facts (a), (b), (c) and (d) are true for Collision Theory.

*Multiple options can be correct
QUESTION: 22

Consider the endothermic reaction,  X→Y

Heat o f reaction = ΔH with Ef = activation energy of the forw ard reaction.
Eb = activation energy of the backward reaction.
Then
Solution:

Given reaction is an endothermic reaction ΔH > 0.

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