CHEMISTRY CHEMICAL KINETICS

CHEMISTRY CHEMICAL KINETICS

60

CLASS ASSIGNMENT

Questions Based on Classification of Reactions on Basis of Rates, MEASUREMENT of

rate of Reaction and Dependence

1. Nitrogen dioxide (NO2) dissociates into nitric oxide (NO) and oxygen (O2) as follows:

2 22NO 2NO O . If the rate of decrease of concentration of NO2 is 6.0 10–12

mol L–1

s–1

. What will

be the rate of increase of concentration of O2?

(A) 3 10–12

mol L–1

s–1

(B) 6 10–12

mol L–1

s–1

(C) 10–12

mol L–1

s–1

(D) 1.5 10–12

mol L–1

s–1

2. For the reaction2 2 3N 3H 2NH , how are the rate of reaction expression inter-related 2[H ]d

dt and

3[NH ]d

dt?

(A) 32[NH ][H ]1 1

3 2

dd

dt dt (B) 32

[NH ][H ]1 1

2 3

dd

dt dt

(C) 32[NH ][H ]1 1

2 3

dd

dt dt (D) 32

[NH ][H ]1 1

3 2

dd

dt dt

3. Rate of disappearance of SO2 in the reaction, 5 1

2 2 32SO O 2SO is 1.28 10 mol s . The rate of

appearance of SO3 is

(A) 0.64 10–5

mol s–1

(B) 0.32 10–5

mol s–1

(C) 2.56 10–5

mol s–1

(D) 1.28 10–5

mol s–1

4. A reaction is catalysed by H+ ion. In presence of HA, rate constant is 2 10

–3 min

–1 and in presence of

HB rate constant is 1 10–3

, HA and HB both being strong acids, we may conclude:

(A) equilibrium constant is 2

(B) HA is stronger than HB

(C) relative strength of HA to HB is 2

(D) HA is weaker than HB and relative strength is 0.5

5. A gaseous hypothetical chemical equation 2A 4B + C is carried out in a closed vessel. The

concentration of B is found to increase by 5 10–3

mol L–1

in 10 second. The rate of appearance of B is:

(A) 5 10–4

mol L–1

sec–1

(B) 5 10–5

mol L–1

sec–1

(C) 6 10–5

mol L–1

sec–1

(D) 4 10–4

mol L–1

sec–1

6. Which of these does not influence the rate of reaction?

(A) Nature of the reactants (B) Concentration of the reactants

(C) Temperature of the reaction (D) Molecularity of the reaction

7. At room temp., reaction between NO and O2 to give NO2 is fast, while that between CO and O2 is slow. It

is due to:

(A) CO is smaller in size than that of NO

(B) CO is poisonous

(C) Ea for the reaction, 2 22NO O 2NO is less than

2 22CO O 2CO

(D) None of these

CHEMICAL KINETICS CHEMISTRY

61

Questions Based on Rate Constant, Molecularity of a Reaction

8. Rate constant in case of first order reaction is

(A) inversely proportional to the concentration units (B) independent of concentration units

(C) directly proportional to concentration units (D) inversely proportional to square of conc. units.

9. Rate constant of two reactions are given below. Identifying their order of reaction.

(i) k = 5.3 10–2

L mol–1

s–1

(ii) k = 3.8 10–4

s-1

(A) (i) second order, (ii) first order (B) (i) first order, (ii) second order

(C) (i) zero order, (ii) first order (D) (i) second order, (ii) zero order

10. For a general reaction X Y, the plot of conc. of X vs time is an exponential graph. What is the order in

the reaction and what are the units of rate constant?

(A) Zero, mol L–1

s–1

(B) First, mol L–1

s–1

(C) First, s–1

(D) Zero, Lmol–1

s–1

11. The unit of rate constant for a zero order reaction is

(A) litre sec–1

(B) litre mol–1

sec–1

(C) mol litre–1

sec–1

(D) mol sec–1

12. For a reaction X Y, the rate of reaction becomes twenty seven times when the concentration of X is

increased three times. What is the order of the reaction?

(A) 2 (B) 1

(C) 3 (D) 0

13. Which of the following statements is incorrect?

(A) A second order reaction must be a bimolecular elementary reaction.

(B) A bimolecular elementary reaction must be a second order reaction.

(C) Zero order reaction must be a complex reaction.

(D) First order may be complex or elementary reaction.

14. In a reaction 2A + B A2B, the reactant A will disappear at

(A) Half the rate B will decrease (B) The same rate that B will decrease

(C) Twice the rate that B will decrease (D) The same rate that B will A2 B will form

15. In the reaction if the initial rate

at t = 0 is What will be

the value of

at t = 0?

(A) (B)

(C) (D)

Questions Based on Mechanism of Reaction, Integrated rate Equation

16. Catalytic decomposition of hydrogen peroxide is a …. Order reaction

(A) First (B) Second

(C) Third (D) Zero

17. The chemical reaction, 2O3 3O2 proceed as 3 2O O [O] (Fast) ;

3 2[O] O 2O (Slow)

(A) Rate = k [O][O3] (B) Rate = k[O3]2[O2]

–1

(C) Rate = k[O3]2 (D) Rate = k[O2][O]


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18. Consider the reaction, Cl2 (aq) + H2S (aq) → S(s) + 2H+(aq) + 2Cl

–(aq)

Rate equation for this reaction is, rate = k [Cl2] [H2S]. Which of these mechanisms is/are consistent with

this rate equation?

(a) Cl2 + H2S H+ + Cl

– + Cl

+ + HS

– (slow) Cl

+ + HS

– H

+ + Cl

– + S (fast)

(b) H2S H+ + HS

– (fast equilibrium) Cl2 + HS

– 2Cl

– + H

+ + S (slow)

(A) (a) only (B) (b) only

(C) Both (a) and (b) (D) Neither (a) nor (b)

19. The following mechanism has been proposed for the reaction of NO and Br2to form NOBr

NO(g) + Br2(g) NOBr2(g) NOBr2 (g) + NO(g) 2NOBr(g)

If the second step is rate determining step, the order of the reaction with respect to NO(g) is

(A) 0 (B) 3

(C) 2 (D) 1

20. For the reaction 2 2 22NO F 2NO F, following mechanism has been provided:

slow

2 2 2NO F NO F F

fast

2 2NO F NO F

Thus rate expression of the above reaction can be written as:

(A) 2

2 2NO Fr K (B) 2NOr K

(C) 2 2NO Fr K (D) 2Fr K

21. For Zero order reaction the plot of concentration of reactant vs time is (intercept refers to concentration

axis)

(A) Linear with + ve slope and zero intercept (B) Linear with – ve slope and zero intercept

(C) Linear with – ve slope and non-zero intercept (D) Linear with + ve slope and non-zero intercept

22. The rate of change of concentration of A for reaction A product is given by d[A]

dt= k [A]

1/3 the

half-life period of the reaction will be

(A)

2 2

23 30

5

3

3[A ] [(2) 1]

(2) k

(B)

2 2

3 303/ 2[A ] [(2) 1]

k

(C)

k)2(

]1)2[(]A[2/3

3

2

3

2

3

2

o (D)

23

3202 / 3[A ] [(2) 1]

k

23. A products, 3[ ]

dxk A

dt. If a is the initial concentration and (a – x) is the concentration of A after

time t, then rate constant is given by

(A) 1 1 1

( )k

t a x a

(B) 2 2

1 1 1

2 ( )k

t a x a

(C)2.303

loga

kt a x

(D)

xk

t


63

Questions Based on First Order Reaction

24. If a is the initial concentration of the reactant and (a- x) is the concentration at time t for the first – order

reaction (Rate constant k1). then which are correct.

I : 1k tx a 1 e

II: (a – x) = a 50

1

2

yt

where yT

III: 1 10

2.303 aK log

t a x

(A) I, II (B) II, III

(C) I, III (D) I, II, III

25. Concentration of the reactant in first-order is reduced to 2

1

e of its original value after

(natural life = 1k

)

(A) one natural life-time (B) two natural life-time

(C) three natural life-time (D) four natural life-time

26. t1/4 can be taken as the time taken for the concentration of a reactant to drop to 3/4 of its initial value. If

rate constant for a first order reaction is k, then t1/4 can be written as

(A) 0.01/k (B) 0.29/k

(C) 0.69/k (D) 0.75/k

27. Rate of 1st order reaction is 1.5 × 10

–2 mol L

–1 min

–1 at 0.5 M concentration of the reactant. Half life of

the reaction is:

(A) 23.1 min (B) 8.73 min

(C) 7.53 min (D) 0.383 min

28. Consider the following first order competing reactions:

X A + B and Y C + D

if 50% reaction of X was completed when 96% of the reaction of Y was completed, the ratio of their rate

constants (k2/k1) is

(A) 4.06 (B) 0.215

(C) 1.1 (D) 4.65

29. Half life period of a first order reaction is 1386 seconds. The specific rate constant of the reaction is:

(A) 0.5 × 10–2

s–1

(B) 0.5 × 10–3

s–1

(C) 5.0 × 10–2

s–1

(D) 5.0 × 10–5

s–1

30. In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 minutes.

The time taken for the concentration to change from 0.1 M to 0.025 M is

(A) 7.5 min (B) 15 min

(C) 30 min (D) 60 min

31. The reaction: A → B follows first order kinetics. The time taken for 0.8 mol of A to produce 0.6 mol of

B is 1 hour. What is the time taken for conversion of 0.9 mol of A to produce 0.675 mol of B?

(A) 1 hour (B) 0.5 hour

(C) 0.25 hour (D) 2 hour

1k 2k

http://www.questionpapers.net.in/chemistry_questions.html


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32. A substance A decomposes in solution following the first order kinetics. Flask I contains 1L of 1 M

solution of A and flask II contains 100 ml of 0.6 M solution. After 8 hr, the concentration of A in flask I

becomes 0.25 M. What will be time for concentration of A in flask II to become 0.3 M?

(A) 0.4 hr (B) 2.4 hr

(C) 4 hr (D) unpredictable as rate constant is not given

33. In a first order reaction the a

a x was found to be 8 after 10 min. The rate constant is

(A) 2.303 3log 2

10

(B)

2.303 2log3

10

(C) 10 2.303 2 log 3 (D) 10 2.303 3 log 2

Questions Based on Method of Determination of Order of Reaction

34. Van’tHoff’s differential method is an important method to determine the order of reaction. According to

this equation, concentration C and rate of reaction dx

dt are related with order of reaction (n) as

(A)

2 1

1 2

log / / /

log /

dx dt dx dtn

C C

(B)

1 2

1 2

log / / /

log /

dx dt dx dtn

C C

(C)

2 1

2 1

log / / /

/

dx dt dx dtn

C C

(D)

2 1

1 2

log / / /dx dt dx dtn

C C

35. The inversion of cane sugar proceeds with half-life of 600 minute at pH = 5 for any concentration of

sugar. However, if pH = 6, the half-life changes to 60 minute. The rate law expression for sugar inversion

can be written as

(A) r = K[sugar]2[H

+]

0 (B) r = K[sugar]

1[H

+]

0

(C) r = K[sugar]1[H

+]

1 (D) r = K[sugar]

0[H

+]

1

36. The bromination of acetone that occurs in acid solution is represented by the equation

CH3COCH3(aq) + Br2(aq) → CH3COCH2Br(aq) + H+(aq) + Br

–(aq).

Kinetic data were obtained from given rxn. conc.:

Initial concentrations, (M)

[CH3COCH3] [Br2] [H+] Initial Rate

0.30 0.05 0.05 5.7 × 10–5

0.30 0.10 0.05 5.7 × 10–5

0.30 0.10 0.10 1.2 × 10–4

0.40 0.05 0.20 3.1 × 10–4

Based on these data, rate of reaction. is:

(A) rate = k [CH3COCH3] [Br2] (B) rate = k [CH3COCH3] [Br2] [H+]

2

(C) rate = k[CH3COCH3][Br2] [H+] (D) rate = k[CH3COCH3] [H

+]

37. Inversion of sucrose (C12H22O11) is first-order reaction and is studied by measuring angle of rotation at

different interval of time.

C12H22O11 + H2O +H C6H12O6 + C6H12O6

Sucrose Glucose Fructose

d d l

If (r – r0) a and (r – rt) (a – x) (where r0, rt and r are the angle of rotation at the start, at the time t

and at the end of the reaction respectively, then there is 50% inversion when;

(A) r0 = 2rt – r (B) r0 = rt – r

(C) r0 = rt – 2 r (D) r0 = rt + r


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38. For 22

3 2 3 2 34 3Cu NH H O Cu NH H O NH

. Net rate of reaction at any time is given net by:

rate 2+

4 5

3 242.0 10 Cu NH H O 3.0 10

2+

3 2 33Cu NH H O NH

. Correct statements is (are):

(A) Rate constant for forward reaction42 10 (B) Rate constant for backward reaction

53 10

(C) Equilibrium constant for the reaction106.6 10 (D) All of these

39. For the chemical reaction A + B + C kD, it was found that the rate of the reaction doubled

when the concentration of B was doubled, that the rate of reaction doubled when the concentration of

both A and B were doubled, and quadrupled when the concentration of both B and C were doubled. The

order of the reaction is :

(A) 2 (B) 3

(C) 4 (D) 6

Questions Based on Temperature Dependence of k & Collision Theory

40. For an exothermic chemical process occurring in two step as

A + B slow

X fast

AB

The progress of the reaction can be best described by

(A) (B)

(C) (D) all are correct

41. For a first order reaction, the plot of log k against 1/T of a straight line. The slope of the line is equal to

(A) aE

R (B)

2.303

aE R

(C) 2.303

aE (D)

2.303

aE

R

42. The rate constant increases with increasing temperature.

(A) as it is given by Arrhenius equation (B) the average energy of the products increases

(C) Both A and B (D) None

43. If a reaction A + B C is exothermic to the extent of 30 kJ/mol and the forward reaction has an

activation energy of 70 kJ/mol, the activation energy for the reverse reaction is

(A) 30 kJ/mol (B) 40 kJ/mol

(C) 70 kJ/mol (D) 100 kJ/mol

A +B

AB

X

A +B AB

X

AB

X

A + B


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44. In the given graph, the activation energy, Ea for the reverse reaction will be

(A) 150 kJ (B) 50 kJ

(C) 200 kJ (D) 100 kJ

45. In the presence of catalyst, Ea is lowered by 2Kcal at 27°C. Hence rate will be

(A) 20 times (B) 14 times

(C) 28 times (D) 2 times

46. The reactions of higher order are rare because

(A) many bodies collisions involve very high activation energy

(B) many bodies collisions have a very low probability

(C) many bodies collisions are not energetically favoured.

(D) many bodies collisions can take place only in the gaseous phase.

47. Rate constants k1 & k2 for 2 diff. reactions are 1016

× e–2000/T

and 1015

× e–1000/T

, respectively. Temp. at

which k1 = k2 is

(A) 2000/2.303K (B) 2000 K

(C) 1000/2.303K (D) 1000 K

48. Energies of activation for forward and reverse reactions for A2 + B2 2AB are 180 kJ mol–1

&

200 kJ mol-1

resp. The presence of a catalyst lowers the activation energy of both (forward and reverse)

reactions by 100 kJ mol–1

. The enthalpy change of the reaction (A2 + B2 →2AB) in the presence of

catalyst will be (in kJ mol–1

):

(A) 120 (B) 128

(C) 20 (D) 300

49. How much faster would a reaction proceed at 25C than at 0oC if the activation energy is 65 kJ?



50. The energy of activation for a reaction is 100 kJ/mol. Presence of a catalyst lowers the energy of

activation by 75%. The ratio of kcat /kuncat (T = 298 K)

(A) 23.4 × 1015

(B) 9.34 × 1013

(C) 1.39 × 1013

(D) 3.25 × 106

51. The rate constant of an exothermic reaction follows:

(A) Exponential increase with increase of temperature

(B) Exponential decrease with increase of temperature

(C) Linear decrease with increase of temperature

(D) Linear increase with increase of temperature

52. Mark the correct statement about given graph:

(A) X is threshold energy level

(B) Y & Z are Ea for forward and backward rxn. resp.

(C) Q is heat of reaction and reaction is exothermic

(D) All of these


67

53. Effective collisions are those in which molecules must:

(A) Have energy equal to or greater than the threshold energy (B) Have proper orientation

(C) Acquire the energy of activation (D) All of these

54. At room temp., reaction between NO and O2 to give NO2 is fast, while that between CO and O2 is slow. It

is due to:

(A) CO is smaller in size than that of NO

(B) CO is poisonous

(C) Ea for the reaction, 2 22NO O 2NO is less than

2 22CO O 2CO

(D) None of these

Questions Based on Radioactivity

55. In the radioactive change SRQP A

Z

A

Z

A

Z

A

Z

4

1

4

11

, the radioactive emitted in sequence are

(A) ,, (B) ,,

(C) ,, (D) , ,

56. 1 mole of an -emitting nuclide X

Z A (half life = 10 hrs) was placed in sealed container. 4.52 1023

He

atoms will accumulate in the container in

(A) 4.52 Hr (B) 9.4 Hr

(C) 10.10 Hr (D) 20 Hr

57. Arrange the following particles in order of their increasing penetration capacity as the projectiles for

artificial transmutation of elements: Proton (1

1H), -particle (4

2He), Deutron (2

1H), neutron (01n)

(A) 42He <

21H <

11H <

10n (B)

11H <

21H >

10n

(C) 1

1H < 2

1H < 4

2He < 10n (D)

10n <

21H <

42He <

21H

58. Loss of a -particle is equivalent to

(A) increase of one proton (B) decrease of one neutron

(C) combination (A) and (B) (D) none

59. The mass of helium atom of mass number 4 is 4.0026 amu, while that of the neutron and proton are

1.0087 and 1.0078 respectively on the same scale. Hence the binding energy per nucleon in the helium

atom is nearly

(A) 5 MeV (B) 7 MeV

(C) 10 MeV (D) 14 MeV

60. Xx

8 atom is isotonic to Y17

9 atom. The value of x is

(A) 8 (B) 16

(C) 9 (D) 17

61. If 5g of a radioactive substance has a 1

2

t =14 h, 20g of the same substance will have a 1

2

t equal to

(A) 56 h (B) 3.5 h

(C) 14 h (D) 28 h

62. The nuclides Ar40

18 and K41

19 are

(A) isotopes (B) isobars

(C) isotones (D) none of these

63. The radioactivity due to C-14 isotope ( 1

2

t = 6000 yr) of a sample of wood from an ancient tomb was

found to be nearly half that of fresh wood; the tomb is, therefore, about

(A) 3000 years old (B) 6000 years old

(C) 9000 years old (D) 12000 years old


68

64. Two radioactive elements X and Y have half lives of 50 and 100 minutes respectively. Initial sample of both

the elements have same number of atoms. The ratio of the remaining number of X and Y after 200 minutes is:

(A) 2 (B) ½

(C) 4 (D) ¼

65. One mole of A present in a closed vessel undergoes decay as

4

2

AA He24zzsmm

. The volume of He collected at NTP after 20 day (t1/2 A= 10 days) is :

(A) 11.2 litre (B) 22.4 litre

(C) 33.6 litre (D) 67.2 litre

66. Pair of similar radiations is

(A) - and - rays (B) - and X – rays

(C) - and - rays (D) - and X – rays

67. The ratio isotope formed during nuclear reaction 17Cl35

(n. p) is:

(A) 15P32

(B) 16S35

(C) 16S34

(D) 15P34

68. The source of enormous energy of sun is :

(A) fusion of hydrogen to form helium (B) fission of uranium

(C) fusion of deuterium and tritium (D) fusion of tritium of form helium

Questions Based on Parallel Reactions and Series Reaction

69. A consecutive reaction A 1kB 2k

C is characterized by

(A) maxima in the concentration of A (B) maxima in the concentration of B

(C) maxima in the concentration of C (D) high exothermicity

70. For the reaction A 1k B 2k C. If the reactions are of 1st order, then d[B]/dt is equal to

(A) K2[B] (B) + k[A]

(C) K1[A] K2[B] (D) K1[A] + K2[B]

71. For a reaction d[X]/dt is equal to

(A) K1(ax) K1(ax) (B) K2(ax) K1(ax)

(C) K1(ax) + K2(ax) (D) K1(ax) K2(ax)


69

ANSWER KEY

Questions Answers Questions Answers

1 A 37 B

2 A 38 D

3 D 39 A

4 C 40 B

5 A 41 D

6 D 42 A

7 C 43 D

8 B 44 B

9 A 45 C

10 C 46 B

11 C 47 C

12 C 48 C

13 D 49 C

14 C 50 C

15 C 51 A

16 A 52 D

17 B 53 D

18 A 54 C

19 C 55 B

20 C 56 D

21 C 57 A

22 A 58 C

23 C 59 B

24 D 60 B

25 B 61 C

26 B 62 C

27 A 63 B

28 D 64 D

29 B 65 C

30 C 66 D

31 A 67 B

32 C 68 A

33 A 69 B

34 B 70 C

35 B 71 D

36 D


70

HOME ASSIGNMENT

Questions Based on Classification of Reactions on Basis of Rates, Measurement of

Rate of Reaction and Dependence

Subjective Problems

1. For: 2A + B A2B, rate = k [A][B]2 with k = 2.0 10

–6 mol

–2 L

2 s

–1. Calculate the initial rate of reaction

when [A] = 0.1 mol L–1

and [B] = 0.2 mol L. Calculate the rate of reaction after [A] is reduced to 0.06 mol L–1

.

2. At 300C the thermal dissociation of HI is found to be 20%. What will be the equilibrium concentration

of H2 and I2 in the system 2 2H I 2HI at this temperature if the equilibrium concentration of HI in it

be 0.96 mol L-1

?

3. In a reaction, 2AProducts, the concentration of A decreases from 0.5 mol L-1

to 0.4 mol L-1

in 10

minutes. Calculates the rate during this interval.

Objective Problems

4. In acidic medium the rate of reaction between 3BrO

and Br s is given by the expression.

23 +

3

BrOBrO Br H

dK

dt

. It means:

(A) Rate constant of overall reaction is 4 sec-1

.

(B) Rate of reaction is independent of the conc. Of acid

(C) The change in pH of the solution will not affect the rate

(D) Doubling the conc. of H ions will increases the reaction rate by 4 times

5. For the reaction 3 (Ag) → B(g) + C(g) , k is If [A] = 0.5 M, then value of

( ) is:

(A) (B)

(C) (D) None of these

6. For a reaction between gaseous compounds, 2A B C D , the reaction rate = k[A] [B]. If the

volume of the container is made 1

4 of the initial, then what will be the rate of reaction as compared to

the initial rate?


(C) 1

8times (D)

1

16times

7. Which of the following will give maximum amount of product in a given time: (i.e. will react fastest) and

which will have highest rate?

(i) 1 mol each of A and B in a 1 L vessel

(ii) 2 mol each of A and B in a 2L vessel

(iii) 0.2 mol each of A and B in 0.1 L vessel

(A) maximum product : (i), highest rate : (i) (B) maximum product : (ii), highest rate : (ii)

(C) maximum product : (iii), highest rate : (iii) (D) maximum product : (ii) highest rate : (iii)


71


72

8. In a gaseous phase reaction, A2(g) B(g) + 1/2C(g). The increase in pressure from 100 mm to 120 mm

is noticed in 5 minutes. The rate of disappearance of A2 in mm min–1

is :

(A) 4 (B) 8

(C) 16 (D) 2

9. In a reaction 2X → Y, the conc. of X decreases from 3 moles/L to 2.0 moles/L in 5 min. Rate of reaction

is:

(A) 0.1 mol L–1

min–1

(B) 5 mol L–1

min–1

(C) 1 mol L–1

min–1

(D) 0.5 mol L–1

min–1

10. For the reaction,2 5 2 22N O 4NO O ; rate and rate constant are 1.02 10

–4 mol L

–1 s

–1 and 3.4 10

–5

s–1

respectively. The concentration of 2 5N O in mol L–1

will be:

(A) 3.4 10–4

(B) 3.0

(C) 5.2 (D) 3.2 10–5

Questions Based on Rate Constant, Molecularity of a Reaction

Subjective Problems

11. What is the difference between order of a reaction and molecularity?

12. The decomposition reaction of ammonia gas on platinum surface has a rate constant = 2.5 10–4

mol L–1

s–1

. What is the order of the reaction?

13. The conversion of the molecules X to Y follows second order kinetics. If the concentration X is increased

to three times, how will it affect the rate of formation of Y?

14. The data given below is for the reaction, 2 5 2 22N O g 4NO g O g

S. No. 1

2 5N O mol L Rate of disappearance of 1 1

2 5N O molL min

1. 2. 3.

21.13 10 20.84 10 20.62 10

534 10 525 10 518 10

Determine for this reaction

(i) Order of reaction (ii) Rate law (iii) Rate constant

15. For the reaction: 22A B A B the rate 2

k A B with 6 2 2 12.0 10 mol L s .k Calculate the

initial rate of the reaction when 1 1A 0.1 mol L , 0.2 mol L .B Calculate the rate of reaction after

A is reduced to 0.06 mol L-1

Objective Problems

16. Which one of the following statements for the other of a reaction is incorrect?

(A) Order of reaction is always whole number.

(B) Order can be determined only experimentally.

(C) Order is not influenced by stoichiometric coefficient of the reactants

(D) Order of reaction is sum of power to the concentration terms of reactants to express the rate of reaction

17. The constant for the reaction is 2 × 10–4

mol L–1

S–1

. The reaction is :

(A) First order (B) Second order

(C) Third order (D) Zero order

18. The specific rate constant of a first order reaction depends on:

(A) time (B) temperature

(C) conc. of product (D) conc. of the reactants


73

19. For a reaction: 2NO(g) + Cl2(g) 2NOCl(g), when concentration of Cl2 is doubled, the rate of reaction

becomes two times of the original. When the concentration of NO is doubled, the rate becomes four

times. What is the order of the reaction?

(A) 1 (B) 2

(C) 3 (D) 4

20. A reaction in which reactants (R) are converted into products (P) follows second order kinetics. If

concentration of R is increased by four times, what will be the increase in the rate of formation of P?



Questions Based on Mechanism of Reaction, Integrated Rate Equation

Subjective Problems

21. The decomposition of dimethyl ether leads to the formation of CH4, H2 and CO and the reaction rate is

given by Rate 3

23 3CH OCH .k The rate of reaction is followed by increase in pressure in a closed

vessel so the rate can also be expressed in terms of the partial pressure of dimethyl ether i.e.,

3 3

3

2CH OCHRate .k p If the pressure is measured in bar and time in minutes, then what are the units rate

and rate constants?

22. The rate decomposition of ammonia is fonia is found upon the concentration of NH3 according to the

equation:

3 1 3

2 3

NH NH

1 NH

d k

dt k

What will be the order of reaction when:

(i) Concentration of NH3 is very high?

(ii) Concentration of NH3 is very low?

23. The reaction 2A B C D E is found to be first order in A, second order in B and zero order in C.

(i) Give the rate law for the reaction in the form of differential equation.

(ii) What is the effect in rate by increasing concentrations of A, B, and C two times?

24. The reaction 2NO + Cl2 2NOCl is second order in NO and first order in Cl2. In a volume of 2 dm3, 5

mole of nitric oxide and 2 mol of Cl2 were brought together, and the initial rate was 2.4 10–3

mole dm–3

s–1

.

What will be the rate when one-half of the chlorine has reacted?

25. Gaseous cyclobutane isomerizes to butadiene in a first order process which has k = 3.3 10–4

s–1

at

153o C. How many minutes would it take for the isomerization to proceed 40% to completion at this

temperature.

26. For the reaction A B, the rate law expression is

1

2d A

k Adt

. If initial concentration of A is

A0. Calculate

(a) integrated form of the rate expression.

(b) Nature of plot of [A]1/2

vs. time.

(c) half life period.


74

Objective Problems

27. A reaction, 2 2 2A B AB occurs by the following mechanism:

2A A A …….(slow) 2A B AB B …..(fast) A B AB ……(fast). Its order would be:

(A) 3

2 (B) 1

(C) Zero (D) 2

28. The decomposition of N2O5 occurs as, 2 5 2 22N O 4NO O and follows I order kinetics, hence:

(A) The reaction is bimolecular (B) The reaction is unimolecular

(C) 1 0

2

t a (D) None of these

29. Which of the following statement is wrong?

(A) Law of mass action and rate law expressions are same for single step reactions

(B) Both order of reaction and molecularity have normally a maximum value of 3

(C) Order of reaction and molecularity for elementary reactions are same

(D) Molecularity of a complex reaction A + 2B C is 3

30. Following mechanism has been proposed for a reaction:

2A B D E .......A B C D slow ......A C E fast

The rate law expression for the reaction is:

(A) 2

r K A B (B) r K A B

(C) 2

r K A (D) r K A C

31. What will be the rate equation for the reaction 2X + Y Z, if the order of the reaction is zero?

(A) Rate = k[X][Y] (B) Rate = k

(C) Rate = k[X]o[Y] (D) Rate = k[X][Y]

o

32. The overall rate of a reaction is governed by

(A) the rate of fastest intermediate step

(B) the sum total of the rates of all intermediate steps

(C) the average of the rates of all the intermediate steps

(D) the rate of slowest intermediate step.

33. The order of reaction is decided by

(A) temperature

(B) mechanism of reaction as well as relative concentration of reactants

(C) molecularity

(D) pressure.

34. For a chemical reaction, A B, the rate of the reaction is 2 × 10–3

mol dm–3

s–1

when the initial

concentration is 0.05 mol dm–3

. Rate of the same reaction is: 1.6 × 10–2

mol dm–3

s–1

when the initial

concentration is 0.1 mol dm–3

. The order of the reaction is

(A) 0 (B) 3

(C) 1 (D) 2

35. For the reaction, A + B products, it is observed that

(i) On doubling the concentration of A only, the rate of reaction is also doubled.

(ii) On doubling the initial concentration of both A and B, there is change by a factor of 8 in the rate of reaction.

The rate of reaction is given by

(A) rate = k [A] [B] (B) rate = k [A]2 [B]

(C) rate = k [A] [B]2 (D) rate = k [A]

2 [B]

2


75

36. Under the same reaction conditions, initial concentration of 1.386 mol dm-3

of a substance becomes half

in 40 s and 20 s through first order and Zero order kinetics respectively. Ratio 1

0

k

k

of the rate

constants for first order (k1) and zero order (k0) of the reaction is

(A) 0.5 mol-1

dm3 (B) 1.0 mol dm

-3

(C) 1.5 mol dm-3

(D) 2.0 mol-1

dm3

37. Which of the following statements for order of reaction is not correct?

(A) Order can be determined experimentally

(B) Order of a reaction is equal to the sum of the power of concentration terms in differential rate law

(C) It is not affected with the stoichiometric coefficients of the reactants

(D) Order cannot be fractional

Questions Based on First Order Reaction

Subjective Problems

38. A first order reaction has k = 1.5 ×10–6

per second at 200°C. If the reaction is allowed to run for

10 hrs., what percentage of the initial concentration would have changed into the product? What is the

half-life of this reaction?

39. The half time of the first order decomposition of nitramide is 2.1 hour at 15°C.

2 2 2 2NH NO aq. N O H O

If 6.2 g of NH2NO2 is allowed to deompose, calculate (i) time taken for NH2NO2 to decompose 99%, and

(ii) volume of dry N2O produced at this point, measured at STP.

40. Two substances A (t1/2= 5 mins) and B (t1/2 = 15 mins) follow first order kinetics are taken in such a way

that initially [A]= 4[B]. Calculate the time after which the concentration of both the substance will be

equal.

41. A substance reacts according to 1 order kinetics and rate constant for the reaction is 1 10-2

sec-1

. If its

initial concentration is 1M. (a) What is initial rate? (b) What is rate after 1 minute?

42. A reaction is started with 1 mole of a compound A. 75% of the reaction is completed in 1 hour. Calculate

the rate constant

(a) if it is a first order reaction, and

(b) if it is a second order reaction.

43. A reaction is first order in A and second order in B:

(i) Write differential rate equation

(ii) How is the rate affected on increasing the concentration of B three times?

(iii) How is the rate affected when the concentration of both A and B are doubled?

44. The rate constant for the first order reaction is 60 s-1

. How much time will it take to reduce the initial

concentration of the reactant to its th

1

16value?

45. For the first order reaction show that time required for 99% completion is twice the time required for the

completion of 90 % of reaction.

46. A first order reaction has a rate constant value of 0.00510 min-1

. If we begin with 0.10 M concentration

of the reactant, how much of the reactant will remain after 3 hours?

47. The half life for radioactive decay of 14C is 5730 y. An archaeological artifact contained wood has only

80% of the 14C found in a living tree. Estimate the age of the sample.


76

48. Sucrose decomposes in acid solution into glucose and fructose according to the first order rate law, with

1/2 3.0t h. What fraction of sample of sucrose remains after 8 hours?

Objective Problems

49. If a I–order reaction is completed to the extent of 60% and 20% in time intervals, t1 and t2, what is the

ratio t1 : t2?

(A) 6.32 (B) 5.58

(C) 4.11 (D) 8.33

50. The time required for 15% decomposition at an initial conc. of 0.1 M in a first order reaction A

Products, at 80ºC is 25 min, then the time required for decomposition by 0.06 M at an initial conc. of

0.4 M at 353 K is:

(A) 5 min (B) 0.25 min

(C) 25 × ln 2 min (D) 25 min

51. For a first order kinetics, a straight line is obtained by plotting dx

dtagainst:

(A) a – x (B) a + x

(C) log (a – x) (D) initial concentration

52. In a first order reaction the reacting substance has half–life period of ten minutes. What fraction of the

substance will be left after an hour the reaction has occurred?

(A) 1/6 of initial concentration (B) 1/64 of initial concentration

(C) 1/12 of initial concentration (D) 1/32 of initial

53. In a first-order reaction A B, if k is rate constant and initial concentration of the reactant A is 0.5 M

then the half-life is :

(A) 0.693

0.5k (B)

log 2

k

(C) log 2

0.5k (D)

ln 2

k

54. Half life period of 1st order chemical rxn. is 6.93 min. Time required for completion of 99% of chemical

rxn. will be:

(A) 230.3 minutes (B) 23.03 minutes

(C) 46.06 minutes (D) 460.6 minutes

Questions Based on Method of Determination of Order of Reaction

Subjective Problems

55. Consider the reaction: 2 A B C D

Following results were obtained in experiments designed to study the rate of reaction:

Exp. No. Initial concentration (mol L-1

) Initial rate of formation

[A] [B] [D] (m/min)

1. 0.10 0.10 31.5 10

2. 0.20 0.20 33.0 10

3. 0.20 0.40 36.0 10

(i) Write the rate law for the reaction.

(ii) Calculate the value of rate constant for the reaction

(iii) Which of the following possible reaction mechanism is consistent with the rate law?

I. A B C E (slow) A E D (Fast)

II. B C E (slow) A E F (Fast)

A F D (Fast)


77

56. In a pseudo first order hydrolysis of ester in water, the following results were obtained:

t/s 0 30 60 90

[Ester]/mol L-1

0.55 0.31 0.17 0.0085

(i) Calculated the average rate of reaction between the time interval of 30 to 60 seconds.

(ii) Calculate the pseudo first order rate constant for the hydrolysis of ester.

57. The following results have been obtained during the kinetics studies of the reaction: 2A B C D

Experiment -1A /mol L -1B /mol L Initial Rate of Formation of

D/ 1 1mol L min

I 0.1 0.1 36.0 10

II 0.3 0.2 27.2 10

III 0.3 0.4 12.88 10

IV 0.4 0.1 22.40 10

Determine the rate law and the rate constant for the reaction.

58. The reaction between A and B is first A and B is first order with respect to A and zero order with respect

to B. Fill in the blanks in the following table:

Experiment 1A /molL 1B /molL

Initial Rate of Formation

of 1 1D/molL min

I 0.1 0.1 22.0 10

II 0.2 24.0 10

III 0.4 0.4

IV 0.2 22.0 10

Objective Problems

59. The half life for a certain reaction at initial conc. of 0.1 mole/lit. and 0.4 mole/lit. are 3 min 20 sec and 50

sec respectively. The order of the reaction is :

(A) 0 (B) 1

(C) 2 (D) 3

60. What will be the order of reaction and rate constant for a chemical change having log t50% vs. log

concentration (a) curve?

(A) 0,0.5 (B) 1,1

(C) 2, 2 (D) 3,1

61. Which conclusion can be drawn if a graph is plotted between log t50% vs. log [reactant] if it shows an

intercept ‘A’ and tan = 0?

(A) 1/2

11,

.n t

K a (B) 1/2

12,n t

a

(C) 1/2

0.6931,n t

K (D) None of these


78

62. For the decomposition of a compound AB at 600 K, the following data were obtained

[AB] mol dm-3

Rate of decomposition of AB in mol dm-3 s

-1

0.20 82.75 10

0.40 811.0 10

0.60 824.75 10 The order for the decomposition of AB is

(A) 0 (B) 1

(C) 2 (D) 1.5

63. The following data is obtained during the first order thermal decomposition of 2g g s

A B C at

constant volume and temperature

S. No. Time Total pressure in Pascal

1. At the end of 10 minutes 300

2. After completion 200

The rate constant in min-1 is

(A) 0.0693 (B) 6.93

(C) 0.00693 (D) 69.3

64. What is order with respect to A, B , C, respectively

[A] [B] [C] rate (M/sec)

0.2 0.1 0.02 38.08 10

0.1 0.2 0.02 32.01 10

0.1 1.8 0.18 36.03 10

0.2 0.1 0.08 26.464 10

(A) 3

1,1,2

(B) 1

1,1,2

(C) 3

1, , 12 (D)

31, 1,

2

65. The initial rates of reaction 3A + 2B + C Products, at different initial concentrations are given below

Initial rate, Ms–1

[A]0, M [B]0, M [C]0, M

5.0 10–3

0.010 0.005 0.010

5.0 10–3

0.010 0.005 0.015

1.0 10–2

0.010 0.010 0.010

1.25 10–3

0.005 0.005 0.010.

Order with respect to reactants A, B & C are resp.

(A) 3, 2, 0, (B) 3, 2, 1

(C) 2, 2, 0 (D) 2, 1, 0

66. Select the rate law that corresponds to data shown for the following reaction: A B Products

Exp. [A] [B] Initial rate

1.

2.

3.

4.

0.012

0.024

0.024

0.012

0.035

0.070

0.035

0.070

0.1

0.8

0.1

0.8

(A) rate 3

k B (B) rate 4

k B

(C) rate k A B (D) rate 2 2

k A B


79

67. When ethyl acetate was hydrolysed in pressure of 0.1M HCl, the rate constant was found to be

But in presence of 0.1M H2SO4 the rate constant was found to be

Thus it may be concluded that:

(A) H2SO4 furnishes more H+ than HCl

(B) H2SO4 furnishes less H+ than HCl

(C) Both have same strength

(D) Will depend on concentration of ethyl acetate.

68. High temperature decomposition of dimethyl ether obeys the first order kinetics:

3 4 22CH O CH H CO

Time (sec) 0 400 x

Total pressure (mm) 312 468 585 y

Value of (x, y) missing above are:

(A) 800, 936x y (B) 620, 624x y

(C) 800, 624x y (D) 620, 936x y

69. Two first order reaction have half lives in the ratio 8:1. Calculate the ratio of time intervals t1: t2.

The time t1 & t2 are the time periods for (

) (

) the completion.

(A) 1: 0.301 (B) 0.125: 0.602

(C) 1: 0.602 (D) None of these

Questions Based on Temperature Dependence of k & Collision Theory

Subjective Problems

70. The specific rate constant for a reaction increases by a factor of 4, if the temperature is changed from

27°C to 47°C. Find the activation energy for the reaction.

71. Use the diagram below to answer the following questions.

(a) Is the reaction exothermic or endothermic?

(b) What is the approximate value of H for the forward reaction?

(c) What is activation energy in each direction?

(d) A catalyst is found that lowers the activation energy of the reaction by about 10kJ/mol. How will this

catalyst affect the rate of the reverse reaction?

72. The rate of reaction triples when temperature changes from 020 C to 050 C . Calculate energy of

activation of reaction. [ Given R = 8.314 J mol–1

K–1

]

73. 1 2t of a first order reaction at 27°C is 100 minutes. 610 % of the reactant molecules exists in the

activated state at 27°C. Calculate the maximum rate constant of the reaction.

74. A first order reaction, A B , requires activation energy of 70 kJ mol-1. When a 20% solution of A was

kept at 25°C for 20 minutes, 25% decomposition took place. What will be the percent decomposition in

the same time in a 30% solution maintained at 40°C? Assume that activation energy remains constant in

this range of temperature.

75. Calculate the decomposition of nitrous oxide by gold at 900°C at an initial pressure of 200 mm was 50% in

53 minute and 73% in 100 minute. (A) What is the order of reaction? (B) Calculate velocity constant. (C)

How much will it decompose in 100 minute at the same temperature but at an initial pressure of 600 mm?


80

76. The rate constant for the decomposition of hydrocarbons is 5 12.418 10 s at 546 K. If the energy of

activation is 179.9 kJ mol-1

, what will be the value of pre-exponential factor?

77. The rate constant for the first order decomposition of H2O2 is given by the equation: 4logk 14.34 1.25 10 K/T

Calculate Ea for this reaction and at what temperature will its 1/2t be 256 minutes?

78. The time required for 10% completion of a first order reaction at 298 K is equal to that required for its

25% completion at 308 K. If the value of A is 10 14 10 s , calculate k at 318 K and aE ?

Objective Problems

79. Unit of frequency factor A in: /aE RT

K Ae

is:

(A) time–1

(B) mol litre–1

time–1

(C) litre mol–1

time–1

(D) dependent of order of reaction

80. In a reaction, the threshold energy is equal to:

(A) activation energy + normal energy of reactants (B) activation energy – normal energy of reactants

(C) normal energy of reactants – activation energy (D) average kinetic energy of molecules of reactants

81. According to collision theory

(A) all collisions are sufficiently violent

(B) all collisions are responsible for product formation

(C) all collisions are effective

(D) only a fraction of collisions are effective which have enough energy to form products

82. The activation energy of the reaction

A + B C + D + 38 kcal is 20kcal. What would be the activation energy for C + D A + B

(A) 20 kcal (B) –20 kcal

(C) 18 kcal (D) 58 kcal

83. In a reaction Product, rate is doubled when the concentration of B is doubled, and rate increases

by a factor of 8 when the concentrations of the reactants (A+B) are doubled, rate law for the reaction can

be written as (A) Rate = k[A][B] (B) Rate = k[A]

2[B]

(C) Rate = k[A][B]2 (D) Rate = k[A]

2[B]

2 84. According to the collision theory of chemical reactions

(A) A chemical reaction occurs with every molecular collision

(B) Rate is directly proportional to the number of collisions per second

(C) Reactions in the gas phase are always of zero order

(D) Reaction rates are of the order of molecular speeds

85. For a first order reaction ,A P the temperature (T) dependent rate constant (k) was found to follow the

equation 1

log 2000 6.0kT

. The pre-exponential factor A and the activation energy Ea,

respectively, are

(A) 6 11.0 10 s and 19.2kJ mol (B)

16.0s and 116.6kJ mol

(C) 6 11.0 10 s and 116.6kJ mol (D) 6 11.0 10 s and

138.3kJ mol

86. An endothermic reaction A B has an activation energy 15 kcal/mole and energy of reaction 5

kcal/mole. The activation energy of the reaction B A is

(A) 20 kcal/mole (B) 15 kcal/mole

(C) 10 kcal/mole (D) None of these


81

87. An endothermic reaction with high activation energy for the forward reaction is given by the diagram

(A) (B)

(C) (D)

88. For a chemical reaction at 27 C, the activation energy is 600 R. The ratio of the rate constants at 327C

to that of a 27 C will be

(A) 2 (B) 4

(C) e (D) e2

89. A reaction take place in three rate determining steps having rate constants K1, K2, K3 respectively. The

overall rate constant 1 3

2

K KK

K . If energy of activations for the three steps are respectively 10, 20, 40

kJ. The overall energy of activation is:

(A) 30 kJ (B) 20 kJ

(C) 10 kJ (D) 70 kJ

90. Rate of which reactions increase with temperature?

(A) of any reaction (B) of exothermic reactions

(C) of endothermic reaction (D) none

91. Fig. shows a graph in T

vsK1

.log10where K is rate constant & T is temp. Straight line BC has slope,

tan = 303.2

1 and an intercept of 5 on y-axis. Thus Ea, the energy of activation is:

(A) 2.303 2 cal (B) 2/2.303 cal

(C) 2 cal (D) None of these

92.

this means that

(A) Rate increases with rise of temperature

(B) Rate decreases with rise of temperature

(C) Rate does not change with rise in the temperature.

(D) None of the above

93. A reaction having equal activation energies for forward and reverse reaction has:

(A) H = 0 (B) S = 0

(C) zero order (D) none of these


82

Questions Based on Radioactivity

Subjective Problems

94. Th234

disintegrates and emits 6- and 7-particles to form a stable product. Find the atomic number and

mass number of the stable product and also identify the element.

95. On of the hazards of nuclear explosion is the generation of 90

Sr and its subsequent incorporation in bones.

This nuclide has a half-life of 28.1 year. Suppose one microgram was absorbed by a new-born child, how

much Sr90

will remain in his bones after 20 year?

96. A certain radio isotope A

Z 1/2X 10t decays to given vessel, how much He will accumulate in 20 day

at STP?

Objective Problems

97. Number of atoms decayed in a half lives, if N0 is initial atoms and N are atoms left after n half lives is

(A) 2n

N (B) 0

2n

N

(C) 0

2 1

2

n

nN

(D)2 1

2

n

n

98. The average life of U238

having 1/2 138.5t days is

(A) 100 days (B) 99.9 days

(C) 199.9 days (D) 138.5 days

99. If (3/4)th quantity of a radioactive element disintegrates in two hours, its half-life would be

(A) 1 hour (B) 45m

(C) 30m (D) 15m

100. A sample of rock from moon contains equal number of atoms of uranium and lead

( 1

2

t for U= years105.4 9 ). The age of the rock would be

(A) 4.5 years109 (B) 9 years109

(C) 13.5 years109 (D) 2.25 years109

101. In – decay, n/p ratio :

(A) may increases or decrease (B) remains constant

(C) decreases (D) increases

102. If – decay, n/p ratio :

(A) remains unchanged (B) may increase or decrease

(C) increases (D) decreases

103. If n/p ratio is high, the nucleus tends to stabilize by :

(A) the emission of a - particle (B) neutron capture

(C) losing a positron (D) any one of these

104. Which is the SI unit of radioactivity?

(A) Einstein (B) Becquerel

(C) Curie (D) Moseley

105. Radium is a radioactive substance. If dissolves in dilute H2SO4 and forms a compound radium sulphate.

The compound is :

(A) no longer radioactive (B) half as radioactive as the radium content

(C) as radioactive as the radium content (D) twice as radioactive as the radium content


83

106. The ionizing power of - , - and - rays is in the decreasing order:

(A) (B)

(C) (D)

107. Which nuclear reaction is not correct:

(A) 63

Cu29(p, 1H2)

62Cu29 (B)

9Be4( , 0n

1) 6C

12

(C) 5Be10

( , 0n1) 7N

13 (D) 27Co

59 (0n

1 , 1H

2 )

62Mn25

108. How many and particles should be eliminated so that an isodiaphere is formed:

(A) n, n (B) 1n n

(C) n (D) n

Questions Based on Parallel Reactions and Series Reaction

Subjective Problems

109. A substance undergoes first order decomposition. The decomposition follows two parallel first order

reactions as

; k1 = 1.26 ×10-4

sec-1

and k2 = 3.6 ×10-5

sec-1

. Calculate the % distribution of B & C.

110. n number of second order reactions are occurring as A is getting converted

into different products B,C,D……

Find out

(A) Net rate constant of the overall reaction.

(B) Is it true that ratio of concentration of different products is equal to ratio

of respective rate constants?

111. 31 2

o

kk k

[A ]A B C D

nk

..... If n numbers of first

order reactions are now occurring, as shown above.

(A) Can we find the net rate constant of the reactions as easily as in the last case

(B) Calculate the formation of C as a function of time. It is given that initial concentration of A is [ ]oA

For

1 2

0

k k

AA B C

112. Write a stoichiometric equation for the reaction whose mechanism is detailed below. Determine the value

of the equilibrium constant for the first step. Write a rate law equation for the overall reaction in terms of

its initial reactants.

2A 2A k1= 1010

s-1

(forward)

k–1 = 1010

M–1

s–1

(reverse)

A C AC k2 = 10-4

M–1

s–1

(slow)


84

ANSWER KEY

Questions Answers Question

s Answers

Question

s Answers

1 8 10–9 39 13.96 hrs ; 2.2176 l 76 3.9 1012

2 0.12 40 15 77 239.34 kJ mol–1 ;

668.8 K

3 5 10–3 41 (a) 1 10–2 (b) 5.49

10–3 78

1.042 10–2 ; 76.623

kJ mol–1

4 D 42 1.38; 3 79 D

5 D 43 (ii) 9; (iii) 8 80 A

6 A 44 4.62 10–2 81 D

7 D 46 0.04 82 D

8 B 47 1845 83 B

9 A 48 0.158 84 B

10 B 49 C 85 D

11 50 D 86 C

12 Zero 51 A 87 C

13 9 52 B 88 C

14 (i) 1 (iii) 3

10–2 53 D 89 A

15 8 10–9; 3.89

10–9 54 C 90 A

16 A 55 (ii) 15 10–3 91 A

17 D 56 (i) 4.67 10–3 92 A

18 B 57 6 93 A

19 C 59 C 94 206

82 Pb.

20 C 60 A 95 6.1 10–7 g

23 (ii) 8 61 C 96 16800 ml

24 4.32 10–4 62 C 97 C

25 26 63 A 98 C

27 B 64 D 99 A

28 B 65 D 100 A

29 D 66 A 101 A

30 B 67 A 102 D

31 B 68 A 103 A

32 D 69 C 104 B

33 B 70 55.32 105 C

34 B 71

(b) 20 kJ/mol

(c) 60 kJ mol–1

(d) 40 kJ mol–1

106 A


85

35 C 72 28.8 kJ mol–1 107 D

36 A 73 6.93 105 108 C

37 D 74 67.2 % 109 77.78 ; 22.22

38 5.26% ; 4.62

105 s 75

(a) 1 (b) 1.308 10–

2 (c) 73% 110

(a) k1 + k2 + …. kn (b)

Yes


86

OBJECTIVE QUESTIONS BANK

1. For a certain reaction of order ‘n’ the time for half change 1

2

t is given by:

1

21 0

2

2 2t C

K

where K is

rate constant and C0 is the initial concentration. The value of n is:

(A) 1 (B) 2

(C) 0 (D) 0.5

2. In the Haber process for the manufacture of ammonia the following catalyst is used

(A) Platinum is used (B) Iron with molybdenum as promoter

(C) Copper oxide (D) Alumina

3. In the first order reaction, half of the reaction is completed in 100 seconds. The time for 99% reaction to

occur will be:

(A) 664.64 s (B) 646.6 s

(C) 660.9 s (D) 654.5 s

4. The rate of a reaction is expressed in different ways as follows:

1 1 1

2 3 4

d C d D d A d B

dt dt dt dt

The reaction is:

(A) 4A + B 2C + 3D (B) B + 3D 4A + 2C

(C) 4A + 2B 2C + 3D (D) B + (1/2)D4A + 3D

5. For the reaction: H2 + Br2 2HBr overall order is found to be 3/2. The rate of reaction can be expressed

as:

(A) [H2] [Br2]1/2 (B) [H2]

1/2 [Br2]

(C) [H2]3/2

[Br2]0 (D) Any of these is possible

6. The rate of a gaseous reaction is given by the expression k[A]2[B]

3. The volume of the reaction vessed is

reduced to one half of the initial volume. What will be the reaction rate as compared to the original rate a?

(A) a8

1 (B) a

2

1

(C) 2a (D) 32a

7. The unit of rate and rate constant are same for a

(A) zero order reaction (B) first order reaction

(C) second order reaction (D) third order reaction

8. For a reaction A + B → C + D if the concentration of A is doubled without altering the concentration of

B, the rate gets doubled. If the concentration of B is increased by nine times without altering the

concentration of A, the rate gets tripled. The order of the reaction is

(A) 2 (B) 1

(C) 3/2 (D) 4/3

9. In a reaction 2HI → H2 + I2, the concentration of HI decrease from 0.5 moL–1

to 0.4 moL–1

in 10 minutes.

What is the rate of reaction during this interval?

(A) 5 10–3

M min–1

(B) 2.5 10–3

M min–1


87

(C) 5 10–2

M min–1

(D) 2.5 10–2

M min–1

10. For 3 2 22NH N 3H , if 3 21 3

[NH ] [N ][NH ],

d dk

dt dt 2

2 3 3 3

[H ][NH ], [NH ]

dk k

dt then the relation

between k1 k2 and k3 is

(A) k1 = k2 = k3 (B) k1 = 3k2 = 2k3

(C) 1.5k1 = 3k2 = k3 (D) 2k1 = k2 = 3k3

11. For the reaction 4NH3 + 5O2 4NO + 6H2O, if the rates of disappearance of NH3 is 3.6 10–3

mol L–1

s–1

,

what is the rate of formation of H2O?

(A) 5.4 10–3

mol L–1

s–1

(B) 3.6 10–3

mol L–1

s–1

(C) 4 10–4

mol L–1

s–1

(D) 0.6 10–4

mol L–1

s–1

12. Reaction N2O5 (in CCl4 solution) 2NO2 (solution) + 2( )

1O

2g is of first order in N2O5 with rate

constant 6.2 10–3

s–1

. What is the value of rate of reaction when [N2O5] = 1.25 mol L–1

?

(A) 7.75 10–1

mol L–1

s–1

(B) 6.35 10–3

mol L–1

s–1

(C) 5.15 10–5

mol L–1

s–1

(D) 3.85 10–1

mol L–1

s–1

13. 1st order reaction is half completed in 45 minutes. How long does it need 99.9% of the reaction to be

completed?

(A) 5 hours (B) 7.5 hours

(C) 10 hours (D) 20 hours

14. 75% of a first order reaction was completed in 32 minutes when was 50% of the reaction completed?

(A) 16 min. (B) 24 min.

(C) 8 min. (D) 4 min.

15. The rate of law for the reaction: Sucrose + water +[H ] Glucose + fructose is given by

(A) Rate = K[sucrose][water] (B) Rate = K[sucrose][water]0

(C) Rate = K[sucrose]0 [water] (D) Rate = K[sucrose]

1/2 [water]

1/2

16. Time for half life period of a certain reaction A → Products is 1 h. When the initial concentration of the

reactant 'A' is 2.0 mol L–1

, how much time does it take for its concentration to come from 0.50 to 0.25

mol L–1

, if it is a zero order reaction?

(A) 0.25 h (B) 1h

(C) 4h (D) 0.5 h

17. For the first order reaction A B + C, carried out at 270C if of the reactant molecules

exists in the activated state, the Ea (activation energy) of the reaction is

(A) 12 kJ/ mole (B) 831.4 kJ/ mole

(C) 100 kJ/ mole (D) 88.57 kJ/ mole

18. The half-life for a reaction is …… of temperature:

(A) Independent (B) Increased with increase

(C) Decreased with increase (D) Dependent

19. A first order reaction is 50% completed in 141.26 10 .s How much time would it take for 100%

completion?

(A) 151.26 10 s (B) 142.52 10 s

(C) 282.52 10 s (D) Infinite


88

20. The decomposition of dimethyl ether is a fractional order reaction is given by rate = 3 3

3/2

CH OCH( ) .k p If

the pressure is measured in bar and time in minutes, then what are the units of rate and rate constant?

(A) bar min–1

, bar2 min

–1 (B) bar min

–1, bar

–1/2 min

–1

(C) bar-1/2

min–1

, bar2 min

–1 (D) bar min

–1, bar

1/2 min

–1

21. The acid catalyzed ionization of γ hydroxyl butyric acid proceeds as a reversible reaction. Which is I

order in both the forward and backward steps:

1

2

K

K LactoseAcid

A B . The rate d A

dt is given by:

(A) 1K A (B) 2K B

(C) 1 2K A K B (D)

1

2

K A

K B

22. For I– + OCl

–IO

– + Cl

– in aq. medium, rate of reaction is given by

[IO ] [I ][OCl ].

[ ]

dk

dt OH

Overall

order of reaction is:

(A) –1 (B) 0

(C) 1 (D) 2

23. Consider the reaction, 2A + B → Products. When conc. of B alone was doubled, half-life did not change.

When conc. of A alone was doubled, the rate increased by two times. The unit of rate constant for this

reaction is:

(A) no unit (B) mol L–1

s–1

(C) s–1

(D) L mol–1

s–1

24. -particle in radioactivity is emitted by:

(A) Conversion of proton to neutron (B) Outermost orbit

(C) Conversion of neutron to proton (D) -particle is not emitted

25. The half-life of a radioisotope is four hour. If the initial mass of the isotope was 200g, the mass left after

24 hour undecayed is:

(A) 4.167 g (B) 2.084 g

(C) 3.125 g (D) 1.042 g

26. In the transformation of 238

92 U to 234

92 U , if one emission is an -particle, what should be the other

emission(s)?

(A) Two – (B) Two

– and one

+

(C) One – and one (D) One

+ and one

–

27. A positron is emitted from 11Na23

. The ratio of the atomic mass and atomic number of the resulting

nuclide is:

(A) 22

10 (B)

22

11

(C) 23

10 (D)

23

12

28. What is the activation energy for a reaction if its rate doubles when the temperature is raised from 20oC

to 35oC? (R = 8.314 JK

–1mol

–1)

(A) 342 kJ mol–1

(B) 269 kJ mol–1

(C) 34.7 kJ mol–1

(D) 15.1 kJ mol–1


89

29. Which of the following can show -emission?

(A) 81 0 81

37 1 36Rb+ Kr .....e (B) 11 11

6 5C B .......

(C) 14 4 17

7 2 8N He O .... (D) 60 60

27 27Co Co ....

30. -radiations from a radioactive element may by produced:

(A) Directly without emission of or -particles

(B) Simultaneously with emission of or -particles

(C) subsequently with emission of - or particles

(D) Never

31. Two elements P and Q have half-life of 10 and 15 minutes respectively. Freshly prepared sample of

mixture containing equal number of atoms is allowed to decay for 30 minutes. The ratio of number of

atoms of P and Q left in mixture is :

(A) 0.5 (B) 2.0

(C) 3.0 (D) 4.0

32. The nuclear reaction, 63 4 37 1 1

29 2 17 1 0Cu He Cl 14 H 16 n represents:

(A) Artificial fission (B) Induced radioactivity

(C) Nuclear fission (D) Spallation reaction

33. Activation energy for a simple chemical rxn. A B is Ea in forward direction. Activation energy for

reverse reaction:

(A) is always double of Ea (B) is negative of Ea

(C) is always less than Ea (D) can be less than or more than Ea

34. Activation energy for a reaction is 9 kcal/mol. The increase in the rate constant when its temperature is

increased from 298 K to 308 K is:

(A) 10% (B) 100%

(C) 50% (D) 63%

35. The energies of activation for forward and reverse reactions for 2 2 2A B AB are 180 kJ mol-1

and

200 kJ mol–1

respectively. The presence of catalyst lowers the activation energy of both (forward and

reverse) reactions by 100 kJ mol-1

. The enthalpy change of the reaction 2 2 2A B AB in the

presence of catalyst will be (in kJ mol–1

)

(A) 300 (B) 120

(C) 280 (D) 20

36. According to Arrhenius theory, the activation energy is

(A) The energy it should possess so that it can enter into an effective collision

(B) The energy which the molecule should possess in order to undergo reaction

(C) The energy it has to acquire further so that it can enter into a effective collision

(D) The energy gained by the molecules on colliding with another molecule

37. Rate of a reaction can be expressed by Arrhenius equation as: k = Ae–E/RT

. In this equation, E represents

(A) the energy below which colliding molecules will not react.

(B) the total energy of the reacting molecules at a temperature, T.

(C) the fraction of molecules with energy greater than the activation energy.

(D) the energy above which all the colliding molecules will react.


90

38. Velocity constant of a rxn. at 290 K was found to be 3.2 × 10–3

s–1

. When the temp. is raised to 310 K, it

will be about:

(A) 9.6 × 10–3

(B) 1.28 × 10–2

(C) 6.4 × 10–3

(D) 3.2 × 10–4

39. In respect of the equation K = Ae–Ea / RT

in chemical kinetics, which one of the following statements is

correct?

(A) k is equilibrium constant (B) A is adsorption factor

(C) Ea is energy of activation (D) R is Rydberg's constant

40. Which of the following has maximum n/p ratio?

(A) 16

Ne (B) 16

O

(C) 16

F (D) 16

N

41. A nuclear reaction is accompanied by a loss of mass equal to 0.0186 amu. The energy liberated in the

process is–

(A) 186 MeV (B) 18.6 MeV

(C) 173 MeV (D) 17.3 MeV

42. Choose the incorrect option-

(A) Among , and rays, ray has highest penetration power

(B) ray has highest velocity

(C) ray has highest ionization power

(D) particle is also called helium nucleus.

43. In the nuclear reaction U23892 Pb206

82 . The number of and particles emitted are–

(A) 7, 5 (B) 6 , 4

(C) 4, 3 (D) 8, 6

44. The end product of (4n + 2) disintegration series the–

(A) Pb20482 (B) Pb208

82

(C) Pb20982 (D) Pb206

82

45. During a negative -decay–

(A) An atomic electron is ejected

(B) An electron which is already present in nucleus is ejected.

(C) A neutron in the nucleus decays emitting an electron

(D) A part of the binding energy o the nucleus is converted into an electron

46. -emission is caused by the transformation of one neutron into a proton. This results in the formation of a

new element having –

(A) Nuclear charge higher by 1 unit (B) Nuclear charge lower by 1 unit

(C) Same nuclear charge (D) None of these 47. What are the and particles are emitted in the nuclear reaction 90Th

228 83Bi

212

(A) Four alpha and one beta (B) Three alpha and seven beta

(C) Eight alpha and one beta (D) One alpha and four beta

48. In the reaction Po –

Pb –

Bi, if Bi belongs to group 15, to which group Po, belongs–

(A) 14 (B) 15

(C) 13 (D) 16


91

49. The number of -particles emitted by

Ra21884 Pb206

82 is–

(A) 3 (B) 4

(C) 6 (D) 2

50. In the decay series

A –

B –

C –

D

(A) A and B are isobars (B) A and C are isobars

(C) A and D are isotopes (D) B and C are isotopes

51. A radioactive element has atomic mass 90 amu and a half-life of 28 years. The number of disintegrations

per second per gm of the element is–

(A) 5.24 × 1010

(B) 5.24 × 108

(C) 5.24 × 10–10

(D) 5.24 × 1012

52. If 8.0 g of a radioactive isotope has a half life of 10 h, the half-life of 2.2 g of the same substance is –

(A) 2.6 h (B) 5 h

(C) 10 h (D) 40 h

53. If the amount of radioactive substance is increases three times, the number of disintegrating atoms per

unit time will be–

(A) Doubled (B) One - third

(C) Triple (D) Uncharged

54. A human body required the 0.01 µ activity of radioactive substance after 24 hours. Half life of

radioactive is 6 hours. Then injection of maximum activity of radioactive substance that can be injected -

(A) 0.08 (B) 0.04

(C) 0.16 (D) 0.32

55. An old sample of wood from an archaeological excavation was found to have a radioactivity of about 8.8

counts per minute due to 14

C (t1/2 = 5700 years) as against 15.3 counts per minute for that of a freshly cut

piece of wood. The age of the old sample of wood is nearly–

(A) 9000 years (B) 7000 years

(C) 4500 years (D) 2500 years

56. In the reaction Be94 + X B10

5 + , X is–

(A) proton (B) deuteron

(C) -particle (D) neutron

57. The reaction 2 3 4 1

1 1 2 0D T He n , is an example of–

(A) nuclear fission (B) nuclear fusion

(C) artificial radioactivity (D) radioactive disintegration

58. Which of the following nuclear changes is incorrect–

(A) 20Ca40

+ 0n1 19K

40 + 1H

1 (B) 12Mg

24 + 14Si

27 + 0n

1

(C) 48Cd113

+ 0n1 48Cd

112 + –1e

0 (D) 20Ca

43 + 21Sc

46 + 1H

1

59. Nuclear reactors are based on–

(A) natural radioactivity (B) nuclear fission

(C) nuclear fusion (D) spontaneous chemical reaction


92

60. Activation energy of a reaction depends on

(A) Nature of reactants (B) Temperature

(C) Conc. of reactants (D) Presence of catalyst

61. For a reaction activation energy for the forward reaction is 50 kJ and for backward reaction is 30 kJ.

Which of the following are true for the reaction?

(A) Reaction is endothermic (B) Reaction is exothermic

(C) Threshold energy is 80 kJ (D) E = 20 kJ

62. The rate law for the reaction,

RCl + NaOH(aq) ROH + NaCl

is given by rate = k[RCl]. The rate of the reaction will be – (A) doubled on doubling the concentration of sodium hydroxide

(B) halved by reducing the concentration of alkyl halide to one-half

(C) increased on increasing the temperature of the reaction

(D) unaffected by increasing the temperature of the reaction.

63. For producing the effective collisions, the colliding molecules must possess

(A) Proper orientation (B) Energy equal to activation energy

(C) Energy equal to or greater than threshold energy (D) Energy greater than threshold energy

64. Which of the following expressions are correct?

(A) kAe–RT/Ea (B) ln k = ln A +

Ea

RT

(C) log k = log A – 2.303

Ea

RT (D) ln A = ln k +

Ea

RT

65. Which of the following graphs for a first order reaction (A Products) would be straight line?

(A) rate versus [A] (B) rate versus time

(C) log [A] versus time (D) Rate versus log [A]

66. A zero order reaction is one –

(A) In which reactants to not react (B) In which one of the reactants is in large excess

(C) Whose rate does not change with time (D) Whose rate increase with time

67. For a given reaction the concentration of the reactant plotted against time gave a straight line with negative

slope. The order of the reaction is-

(A) 3 (B) 2

(C) 1 (D) 0

68. Decomposition of NH4NO2 (aq) into N2(g) and 2H2O(l) is first order reaction. Which of the following

graph is correct?


36

(A) (B)

(C) (D)

69. If 'a' is the initial concentration of a substance which reacts according to zero order kinetic and k is rate

constant, the time for the reaction to go to completion is

(A) a

k (B)

2

ka

(C) k

a (D) infinite

70. If for any reaction, the rate constant is equal to the rate of the reaction at all concentration, the order is–

(A) 0 (B) 2

(C) 1 (D) 3

71. For a certain reaction involving a single reactant, it is found that 0C T is constant where C0 is the initial

concentration of the reactant and T is the half-life. What is the order of the reaction?

(A) 1 (B) zero

(C) 2 (D) 3

72. For the irreversible unimolecular type reaction A k products in a batch reactor, 80% reactant A(CA0

= 1 mole/lit.) is converted in a 480 second run and conversion is 90% after 18 minute. The order of this

reaction is -

(A) 1 (B) 2

(C) 1/2 (D) 3/2

73. For the first order reaction 99% 90%t x t the value of 'x' will be -

(A) 10 (B) 6

(C) 3 (D) 2

74. If in the fermentation of sugar in an enzymatic solution that is 0.12M, the concentration of the sugar is

reduced to 0.06M in 10h and to 0.03M in 20h, what is the order of the reaction–

(A) 1 (B) 2

(C) 3 (D) 0

75. In a Ist order reaction A products, the concentration of the reactant decreases to 6.25% of its initial

value in 80 minutes. What is (i) the rate constant and (ii) the rate of the reaction. 100 minutes after the

starts, if the initial concentration is 0.2 mole/litre?


37

(A) 2.17 × 10–2

min–1

, 3.47 × 10–4

mol. litre–1

min–1

(B) 3.465 × 10–2

min–1

, 2.166 × 10–4

mol. litre–1

min–1

(C) 3.465 × 10–3

min–1

, 2.17 × 10–3

mol. litre–1

min–1

(D) 2.166 × 10–3

min–1

, 2.667 × 10–4

mol. litre–1

min–1


38

76. Rate of a reaction; A + B Products; is given below as a function of different initial concentrations of

A and B

[A] mol litre–1

[B] mol litre–1

Initial rate mol litre–1

time–1

0.01 0.01 0.005

0.02 0.01 0.010

0.01 0.02 0.005

The half life of A in the reaction is :

(A) 13.86 min (B) 1.386 min

(C) 0.01 min (D) 0.01 min

77. The half life period for catalytic decomposition of AB3 at 50 mm is found to be 4 hrs and at 100 mm it is

2.0 hrs. The order of reaction is

(A) 3 (B) 1

(C) 2 (D) 0

78. The decomposition of formic acid on a gold surface follows first order kinetics and specific rate constants

are 5.5 × 10–4

s–1

and 9.2 × 10–3

s–1

at 140°C and 185°C respectively. Energy of activation is

(A) 98.46 J mol–1

(B) 98.46 k J mol–1

(C) 23.7 J mol–1

(D) 23.7 k J mol–1

79. In which of the following case, Ea of the backward reaction is greater than that of the forward reaction?

(A) +10kcal

A B , Ea = 50 kcal (B) +20kcal

A B , Ea = 40 kcal

(C) +40kcal

A B , Ea = 10 kcal (D) 40kcal

A B

, Ea = 20 kcal

80. The half-life of radioactive sodium is 15 hours its disintegration constant is

(A) 0.0462 h–1

(B) 0.0642 h–1

(C) 0.462 s–1

(D) 0.0462 min–1

81. Two radioactive elements X and Y have half-lives of 50 and 100 minute respectively. Initial sample of

both the elements have same number of atoms. The ratio of the remaining number of atoms of X and Y

after 200 minute is:

(A) 2 (B) 1/ 2

(C) 4 (D) 1/4

82. The number of millimoles of 14

6 Cequivalent to one millicuries, if 1/2 5570t year and 1 curie = 3.7 1010

dps is:

(A) 1.56 10–2

(B) 3.12 10–2

(C) 4.34 10–2

(D) 7.80 10–2

83. Which has magic number of neutrons?

(A) 27

13 Al (B) 209

83 Bi

(C) 238

92 U (D) 56

26 Fe

84. Nuclides having same atomic number and same mass number but different rate of decay are called :

(A) isotones (B) isobars

(C) nuclear isomers (D) isotopes

85. What is the value of n for the parent element of 4 3n series?

(A) 56 (B) 58

(C) 57 (D) 60


39

86. Isodiaphers are atoms having:

(A) p/n constant (B) (p – n) constant

(C) (n – p) constant (D) (n – p) different

87. The isotope used to find the age of relics:

(A) 13

7 N (B) 12

6 C

(C) 266

88 Ra (D) 14

6 C

88. The parent nucleus of 4 3n series is:

(A) 228

Ac (B) 235

U

(C) 238

U (D) 237Th

89. In a reaction, 2X Y, the concentration of X decreases from 0.50 M to 0.38 M in 10 min. What is the

rate of reaction in M s–1

during this interval?

(A) 2 10–4

(B) 4 10–2

(C) 2 10–2

(D) 1 10–4

90. For a gaseous reaction, the rate is often expressed in terms of dP

dt

instead of dC dn

ordt dt

where

C is the concentration and n is the number of mole. Hence, relation between three expressions is:

(A) 1 1dC dn dP

dt V dt RT dt

(B) dC dn dP

dt dt dt

(C) dC dn V dP

dt dt RT dt

(D) None of these

91. The instantaneous rate of disappearance of the MnO4– ion in the following reaction is 3 14.569×10 Ms

2MnO4- + 10 I

- + 16 H

- 2Mn

2+ + 5I2 + 8 H2O

The rate of appearance of I2 is:

(A) 1.14×10-3

Ms-1

(B) 5.7 × 10-3

Ms-1

(C) 4.56 × 10-4

Ms-1

(D) 1.14 × 10-2

Ms-1

92. The units of rate constant for the reaction, 2 2 22H 2NO 2H O N which has rate = k[H2][NO]2,is

(A) mol L–1

s–1

(B) s–1

(C) mol–2

L2 s

–1 (D) mol L

–1

93. The rate constant for the reaction, 5 1

2 5 2 22N O 4NO O is 2 10 s .

If rate of reaction is 1.4 10–5

mol L–1

s–1

, what will be the concentration of N2O5 in mol–1

?

(A) 0.8 (B) 0.7

(C) 1.2 (D) 1

94. Rate of: 3 2 5 3 2 5CH COOC H NaOH CH COONa C H OH is given by the equation, rate =

k[CH3COOC2H5][NaOH].

If concentration is expressed in mol/L, the units of k are

(A) mol–2

L–2

s–1

(B) mol L–1

s–1

(C) L mol–1

s–1

(D) s–1

95. For a uni-molecular reaction,

(A) the order and molecularity of the slowest step are equal to one

(B) molecularity of the reaction can be zero, one or two

(C) more than one reacting species are involed in one step

(D) molecularity of the reaction can be determined only experimentally


40

96. The rate law for the reaction RCl + NaOH ROH + NaCl is given by rate = k[RCl]. The rate of this reaction

A. is doubled by doubling the concentration of NaOH

B. is halved by reducing the concentration of RCl by one half

C. is increased by increasing the temperature of the reaction

D. is unaffected by change in temperature

Which is correct?

(A) A and B (B) B and C

(C) C and D (D) B and D

97. The rate law of the reaction A + 2B Product is given by d[Product]/dt = K[A]2[B]. If A is taken in

large excess, the order of the reaction will be

(A) 0 (B) 1

(C) 2 (D) 3

98. The rate of reaction Cl3C.CHO + NO CHCl3 + NO + CO is given by equation,

Rate = k[Cl3.CCHO][NO]. If concentration is expressed in moles/litre, the units of K are

(A) litre²mole2

sec1

(B) mole litre1

sec1

(C) litre mole1

sec1

(D) sec1

99. Rate of the given reaction,

(i) 1 0.05rA B X

(ii) 2 0.89r

X B Y

(iii) )(001.03 AYAY

r

(iv) 4 0.010rAY B AYB

Will be determined by

(A) Step (i) because the reaction starts with the formation of X

(B) Step (ii) because it is fastest step

(C) Step (iii) because it is the slowest step

(D) Step (iv) because it ends the reaction

100. A g B g C g

[ ]

d Ak A

dt

At the start pressure is 100 mm and after 10 min, pressure is 120 mm. Hence rate constant (min-1

) is:

(A) 2.303 120

log10 100

(B) 2.303 100

log10 20

(C) 2.303 100

log10 80

(D) 2.303 100

log10 120

101. Half-life of a third –order reaction is

(A) 50

0.696T

k (B) 50

1T

ka

(C) 502

aT

k (D) 50 2

1.5T

ka


41

102. At the point of intersection of the 2 curves shown, the conc. of B is given by ……. For A nB:

(A) 2

0nA (B)

1

0

n

A

(C) 1

0

n

nA (D)

01

1A

n

n

103. Two first order reactions have half-life in the ratio 3:2 Calculate the ratio of time intervals t1: t2. The time

t1 and t2 are the time period for 25% and 75 % completion for the first and second reaction respectively:

(A) 0.311 : 1 (B) 0.420 : 1

(C) 0.273 : 1 (D) 0.119 : 1

104. For a second order reaction, half-life of reactants is:

(A) Independent of initial concentration of reactants

(B) Directly proportional to concentration of reactants

(C) Inversely proportional to concentration of reactants.

(D) Inversely proportional to square of conc. of reactants

105. 2N Cl Cu/

2N + Cl

Half-life is independent of concentration of A. After 10 minutes volume of N2 gas is 10 L and after

complete reaction volume is 50 L. Hence rate constant is

(A) 2.303

10log 5 min

1 (B)

2.303

10log1.25 min

1

(C) 2.303

10log 2 min

1 (D)

2.303

10log4 min

1

106. For the reaction, of the first order, variation of log T50 with log a (where T50 is half-life period and a is the

initial concentration) is given by

(A) (B)

(C) (D)


42

107. Decomposition of H2O2 (1st order): H2O2(aq) H2O(l) + 1

2O2(g). It can be monitored by titration

method & by pressure measurement. If

Time (min) t = 0 30

Pressure (mm of Hg) 200 375 400

When progress of same reaction was monitored by titration vol. of titrant consumed after 10 min was

found to be 20 ml.

Then find x:

Time (min) t = 0 10 30

Pressure (mm of Hg) 200 300 375

Volume of KMnO4 (ml) 40 20 x

(A) 5 (B) 40

(C) 400 (D) 375

108. Consider endothermic rxn. X Y with activation energies Eb & Ef for backward & forward rxn., resp.,

in general

(A) Eb<Ef (B) Eb>Ef

(C) Eb = Ef (D) There is no definite relation between Eb & Ef

109. For a first order reaction A P, the temperature (T) dependent rate constant (k) was found to follow the

equation

log k = –(2000)1/T + 6. The pre–exponential factor A and the activation energy Ea, respectively, are

(A) 106 s

−1 & 9.2 kJ mol

−1 (B) 6.0 s

−1 & 16.6 kJ mol

−1

(C) 106 s

−1 & 16.6 kJ mol

−1 (D) 10

6 s

−1 & 38.3 kJ mol

−1

110. A reaction takes place by the following mechanism

A + BC AC + B

AC + D A + CD

The potential energy profile for this is shown below:

Transition states are shown by:

(A) I, V (B) II, IV

(C) II, III, IV (D) III only

111. A first order reaction is 50% completed in 20 minutes at 27°C and in 5 min at 47°C. The energy of

activation of the reaction is

(A) 43.85 kJ/mol (B) 55.14 kJ/mol

(C) 11.97 kJ/mol (D) 6.65 kJ/mol

112. The reaction v1A + v2B products is first order with respect to A and zero order with respect to B. If the

reaction is started with [A0] and [B0], the integrated rate expression of this reaction would be-

(A)

0

1

0

lnA

k tA X

(B)

(C)

0

1

10

lnA

k tA v X

(D)

0

1 1

10

lnA

v k tA v X


43

113. When a bio chemical reaction is carried out in laboratory out side the human body in the absence of

enzyme, then the rate of reaction obtained is 10–6

times, than activation energy of reaction in the presence

of enzyme is:

(A) 6/RT (B) P is required

(C) Different from, Ea obtained in laboratory (D) Can't say any things

114. The rate of a reaction gets doubled when the temperature changes from 7C to 17C. By what factor will

it change for the temperature change from 17C to 27C?

(A) 1.81 (B) 1.71

(C) 1.91 (D) 1.76

115. Two reactions, A Products and B Products have rate constants AK and BK at temperature T and

activation energies AE and BE respectively. If A BK K and A BE E and assuming that A for both the

reactions is same then:

(A) At higher temperature KA will be greater than KB

(B) At lower temp. KA & KB will differ more and A BK K

(C) As temp. rises AK & BK will be close to each other in magnitude

(D) All of these

116. Endothermic rxn., A B have Ea = 15 kcal/mol & heat of reaction is 5 kcal/mol. Ea of the reaction,

AB is:

(A) 20 kcal/mol (B) 15 kcal/mol

(C) 10 kcal/mol (D) zero

117. The emission of beta particles is from:

(A) the valence of an atom

(B) the inner shell of an atom

(C) the nucleus due to the nuclear conversion proton neutron + electron

(D) the nucleus due to the nuclear conversion neutron proton + electron

118. If a radioactivity substance is placed in vacuum at 100°C, its rate of disintegration in comparison to one

atmospheric pressure :

(A) is not affected (B) increases

(C) decreases (D) increase when the product is gas.

119. Weight of 14

C6 to have radioactivity 1 curie | (disintegration constant = 4.4 10-12

sec-1

) |is

(A) 2 10-4

kg (B) 0.9 10-4

kg

(C) 1.7 10-4

kg (D) 3.710-10

kg

120. A radioactivity element A decays with a decay constant . The fraction of nuclei that decayed at any

time t, if the initial nuclei are N0 is given by :

(A) te (B) 1 – te

(C) te (D) 1 / ( e – te )

121. A radioactive isotope has initial activity of 28 dpm. Its activity is reduced to 14 dpm after half an hour.

The initial number of nuclide is sample was :

(A) 200 (B) 400

(C) 600 (D) 1211

122. Average life of a radioactive substance is :

(A) 0.44times of half life (B) 2.44 times of half life

(C) 1.44 times of half life (D) 0.693 times of half life


44

123. A radioactive element X, decays by the sequence and with half lives, given below :

X [half life =30 min] 1k Y + Y [ half life = 2 days ] 2k Z + 2

Which of the following statements is correct :

(A) Disintegration constant k2 > k1 (B) Atomic number of X and Z are same

(C) The mass number of Y is greater than X (D) Y and Z are isotopes

124. The isotope 235

U92 decays in a number of steps to an isotope of 207

Pb82. The group of particles emitted in

this process will be :

(A) 4 , 7 (B) 6 , 4

(C) 7 , 4 (D) 10 , 8

125. No. of -particles emitted during the change aXb cY

d :

(A) [(a – d)/ 4] (B) c + [(a – d) / 2] + b

(C) c + [ (b – d) / 2] – a (D) c + [(a – d) / 2] – b

126. When 27

Al13 is bombarded with -particles, a radioactive isotope of phosphorus 30

P15 with the emission

of ……. is formed.

(A) neutrons (B) proton

(C) positrons (D) electrons

127. Number of neutrons in a parent nucleus X which give 7N14

after two successive emission would be :

(A) 9 (B) 6

(C) 7 (D) 8

128. A freshly prepared radioactive source of half period 2 hours emits radiations of intensity which is 64 times the

permissible safe level. The minimum time after which it would be possible to work with source is:

(A) 6 hours (B) 12 hours

(C) 24 hours (D) 48 hours

129. In the nuclear reaction, 14

N7 + 4He2

pXq +

1H1 the nucleus X is

(A) nitrogen of mass 16 (B) nitrogen of mass 17

(C) oxygen of mass 16 (D) oxygen of mass 17

130. Sulphur–35 (34.96903 amu) emits a -particle but no -rays. The product is chlorine–35 (34.96885

amu). The maximum energy carried by - particle is:

(A) 16.758 MeV (B) 1.6758 MeV

(C) 0.16758 Me V (D) 0.016758 MeV

131. The reaction 235

U92 + 1n0

140Ba56 +

93Kr36 + 3

1n0 represent:

(A) artificial radioactivity (B) nuclear fission

(C) Nuclear fusion (D) none of these

132. If two light nuclei are fused together in nuclear reaction, the average energy per nucleon:

(A) Increases (B) Decreases

(C) Cannot be determined (D) Remains same


45

ANSWER KEY

Questions Answers Questions Answers Questions Answers Questions Answers

1 D 34 D 67 D 100 C

2 B 35 D 68 D 101 D

3 A 36 C 69 A 102 C

4 B 37 A 70 A 103 A

5 D 38 B 71 D 104 C

6 D 39 C 72 B 105 B

7 A 40 D 73 D 106 C

8 C 41 D 74 A 107 A

9 A 42 C 75 B 108 A

10 C 43 D 76 B 109 D

11 A 44 D 77 C 110 B

12 A 45 C 78 C 111 B

13 B 46 A 79 A 112 C

14 A 47 A 80 A 113 C

15 B 48 D 81 D 114 C

16 A 49 A 82 A 115 D

17 D 50 C 83 B 116 C

18 C 51 D 84 C 117 D

19 D 52 C 85 B 118 A

20 B 53 C 86 C 119 A

21 C 54 C 87 D 120 B

22 C 55 C 88 B 121 D

23 D 56 A 89 D 122 C

24 C 57 B 90 A 123 B

25 C 58 C 91 D 124 C

26 A 59 B 92 C 125 C

27 C 60 AD 93 B 126 A

28 C 61 AD 94 C 127 A

29 D 62 BC 95 A 128 B

30 C 63 AC 96 A 129 D

31 A 64 CD 97 B 130 C

32 D 65 AC 98 C 131 B

33 D 66 C 99 C 132 C

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