CHEMICAL KINETICS – 2

1) -d [H2O2]/dt represents the
a)
b)
c) Order of reaction
d) None

2) The rate of chemical reaction depends on the nature of chemical reaction because
a) The threshold energy level differs from one reaction to another
b) Some of the reactants are solid at room temp.
c) Some of the reactants are coloured
d) All

3) If concentration units are reduced by n times, then the value of the rate constant of the first order will
a) Increase by n times
b) Decrease by factor of n
c) Not change
d) None

4) For the reaction, 4A + B 2C + 2D, which of the following statements is not correct?
a) The rate of disappearance of B is one fourth the rate of disappearance of A
b) The rate of appearance of C is half the rate of disappearance of B
c) The rate of formation of D is half the rate of consumption of A
d) The rate of formation of C and D are equal

5) Which of the following statements is correct for the reaction X + 2Y Products?
a) The rate of disappearance of X = 2 times rate of disappearance of Y
b) The rate of disappearance of X = 1/2 times rate of appearance of products
c) The rate of appearance of products = 1/2 times rate of disappearance of Y
d) The rate of appearance of products = 1/2 times rate of disappearance of X

6) What is the half life of a radioactive substance if 87.5% of any given amount of the substance disintegrates in 40 minutes ?
a) 160 min
b) 10 min
c) 20 min
d) 13 min. 20 sec

7) When the volume of the reaction vessel is doubled, the rate of the third order reaction 2NO + O2 2NO2,.
a) Will increase to 8 times its initial rate
b) will reduce to one-eighth its initial rate
c) Will increase to 4 times its initial rate
d) will reduce to one-fourth of its initial rate

8) For the elementary step,

(CH3)3CBr(aq) (CH3)3C+ (aq) + Br(aq).

The molecularity is
a) 0
b) 1
c) 2
d) Unpredictable

9) Which statement is correct ?
a) The law of mass action and rate law expressions are the same for single step reactions.
b) The rate of the slowest elementary reaction of a complex reaction determines the order of the complex reaction
c) Both order and molecularity have generally a maximum value of 3
d) All are correct

10) If the rate expression for a chemical reaction is rate = K [A] [B]n, then the order of reaction is
a) 1
b) n
c) n – 1
d) n + 1

11) Which statement about the order of reaction is correct?
a) The order of reaction must be a positive integer
b) A second order reaction is also bimolecular
c) The order of reaction increases with increase in temperature
d) The order of reaction can only be determined by experiment

12) Which statement is correct?
a) Molecularity of a reaction is the same as the order of reaction
b) In some cases the order of reaction may be the same as the molecularity of the reaction
c) The molecularity of a reaction may be fractional
d) All are correct

13) For which order are the units of rate and rate constant the same?
a) Zero
b) First
c) Second
d) Third

14) The correct expression for the rate of reaction of the elementary process A + B C is
a)
b)
c)
d)

15) For a reaction, 2A + B C+ D,

. The expression for

will be
a)
b)
c)
d)

16) The plot of log (a -x) against time t is a straight line. The reaction is of
a) Second order
b) First order
c) Zero order
d) Third order

17) The rate constant for a reaction is 10.8 x 10-5 mol. litre-1 sec-1 . The reaction is
a) First order
b) Second order
c) Zero order
d) Third order

18) The rate law for a reaction A + B Product is rate = k [A]1 [B]2. Then, which one of the following statements is false?
a) If [B] is held constant while [A] is doubled, the reaction will proceed twice as fast
b) If [A] is held constant while [B] is reduced to one quarter, the rate will be halved
c) If [A] and [B] are both doubled, the reaction will proceed 8 times as fast
d) This is a third order reaction

19) For a certain decomposition, the rate is 0.30 M sec-1 when the concentration of the reactant is 0.20 M. If the reaction is second order, the rate (in M sec-1) when the concentration is increased 3-fold is
a) 0.30
b) 0.90
c) 0.60
d) 2.70

20) For a first order reaction A Products, the concentration of [A] is reduced from 1 M to O. 125 M in one hour. The t1/2 of this reaction (in sec) is
a) 600
b) 300
c) 1200
d) 0.693/1200

21) The half – life period for a certain first order reaction is 30 minutes. How long will it take for 1/32 of the reactant to be left behind?
a) 60 minutes
b) 120 minutes
c) 90 minutes
d) 150 minutes

22) In the reaction X + YXY, if the concentration of X and Y are doubled, the rate of reaction will
a) Increase four times
b) Increase two times
c) Decrease two times
d) Decrease to one half

23) The rate constant (k) for the reaction
2A + B product was found to be 2.5 x 10 lit mole-1 sec-1after 15 sec,
2.60 x 10 lit. mole-1sec-1after 30 sec and
2.55 x 10 lit mole-1 sec-1 after 50 sec. The order of reaction is.

a) Two
b) Three
c) Zero
d) One

24) A graph between time t and substance consumed at any time (x) is found to be a straight line through the origin. This indicates that the reaction is of the
a) First order
b) Zero order
c) Third order
d) Second order

25) The half-life period for a reaction at initial concentrations of 0.5 and 1.0 moles litre-1 are 200 sec and 100 sec respectively. The order of the reaction is.
a) Zero
b) 1
c) 2
d) 3

26) If the rate of reaction becomes 2 times for every 10°C rise in temperature, by what factor doed the rate of reaction increase when the temperature is increased from 30°C to 80°C?
a) 16
b) 32
c) 64
d) 128

27) If the concentration units are reduced by M times, then the value of the rate constant of the first order will
a) Increase by M times
b) Decrease by a factor of M
c) Not change
d) None

28) @ In the reaction A , if the concentration of the reactant is increased by 4 times, the rate of reaction is increased by two times. The order of reaction is
a) 0.5
b) 1
c) 2
d) 0

29) The rate expression for a chemical reaction 2NO2F 2NO2+ F2 is given by rate =k [NO2F]. The rate determining step may be
a)
b)
c)
d)

30) For an nth order reaction, the half life period t1/2 is proportional to the initial concentration as
a)
b)
c)
d)

31) The power to which the concentration of a substance appears in the rate expression is known as the
a) Rate of reaction
b) Order of reaction
c) Molecularity of reaction
d) Order of reaction w.r.t. that substance

32) Which of the following is a first order reaction?
a)
b)
c)
d)

33) The rate of reaction between A and B increases by a factor of 100, when the concentration of A is increased by 10 fold. The order of reaction with respect to A is
a) 10
b) 1
c) 4
d) 2

34) In the presence of an acid, the initial concentration of cane sugar was reduced from 0.20 to 0.10 molar in 5 hours and 0.05 molar in 10 hours. The reaction is of
a) Zero order
b) First order
c) Second order
d) Third order

35) The effect of temperature on the reaction rate is given by the
a) Arrhenius equation
b) Gibbs Helmholtz equation
c)
d) None

36) The minimum excess energy necessary to permit a reaction to take place is the
a) Threshold energy
b) Activation energy
c) Free energy
d) Kinetic energy

37) The rate of reaction between two atoms A and B is expressed as dx/dt = K [A] [B]2. On doubling the concentration of both the reactants A and B, the reaction rate is increased
a) 4 times
b) 3 times
c) 8 times
d) 6 times

38) For the hydrolysis of esters in an alkaline medium, the rate equation is expressed as

= k [Ester] [Alkali]

In case alkali used is in excess, then the overall order of the reaction is
a) Zero
b) First
c) Same
d) Third

39) The activation energy for the forward reaction A + B C + D H = -38K.cals is 20 kcals. The activation energy for the same reaction considered in reverse direction is (in k cals)
a) 20
b) -20
c) 58
d) 18

40) When ethyl acetate was hydrolysed in presence of 0.1 N HCl, the rate constant was found to be 5.40 x 10-5 sec-1, but when 0.1 N H2SO4 was used for hydrolysis, the rate constant was found to be 6.20 x 10-5 sec-1.Thus
a)
b)
c)
d)

41) For a slow reaction, the ratio of rate constants at 35°C and 25°C is generally
a) 2
b) 3
c) 1
d) 4

42) The number of atoms or molecules whose concentration alters during a chemical change is its

a) Molecularity
b) Order of reaction
c) Change in reaction
d) None

43) In several experiments on the kinetics of the reaction A + B Products it is found that (i) On doubling the initial concentration of A, the rate was increased four times (ii) On doubling the concentration of B, the rate was increased by two times. Hence the overall order of the reaction is
a) 0
b) 3
c) 2
d) 1

44) For a chemical reaction, A B, it is found that the rate of reaction doubles when the concentration is increased four times. The order of this reaction is.
a) 2
b) 1
c) 0
d) 1/2

45) The rate of a first order reaction A products, is 7.5 X 10-4 mole-1 sec-1 . When the concentration of A is 0.5 mole-1 lit-1 the rate constant is
a)
b)
c)
d)

46) Consider the reaction 2A + B C + D (Rate=k[A]2[B]). If the concentrations of the reactants are increased by three times, the rate of the reaction will increase by.
a) 9 times
b) 81 times
c) 64 times
d) 27 times

47) The rate of reaction A + B Product is proportional to the first power of the concentration of A and 2nd power of the concentration of B. The overall order of the reaction is
a) 1
b) 2
c) 3
d) 0

48) In the reaction A + 2B Products, doubling the concentration of B (keeping the concentration of A constant) increases the rate
a) 2 times
b) 4 times
c) Three times
d) 6 times

49) How much faster would a reaction proceed at 25°C than at 0°C if the activation energy is 65 kJ?
a) 2 Times
b) 16 times
c) 11 times
d) 5 times

50) For a reaction A + B Products, it is observed that doubling the concentration of B causes the reaction rate to increase four times, but doubling the concentration of A has no effect on the rate of reaction. The rate equation is therefore
a)
b)
c)
d)

51) For the reaction A B, the rate of reaction is quadrupled when the concentration of A is doubled. The rate expression for the reaction is r
= k[A]n, when the value of n is

a) 1
b) 0
c) 3
d) 2

52) What will happen to a second order gas phase reaction if the volume of the reaction vessel is doubled.
a) It will be l/4th of the initial value
b) It will be l/6th of is original value
c) It will be 8 times of its initial value
d) It will be 4 times of its initial value

53) As the energy of activation increases,
a) The number of reacting molecules colliding decreases
b) The rate of reaction decreases
c) The rate of reaction increases
d) The rate constant increases

54) The dependence of the rate constant k of a reaction on the activation energy E is expressed as
a) K=Ae-E/RT
b) K=AeE/RT
c)
d)

55) In the first order reaction 75 % of the reactant disappeared in 1.386 hours. Calculate the rate constant of the reaction.
a)
b)
c)
d)

56) The activation energy for a reaction is 9.0 k.cals/mole. The increase in the rate constant when its temperature is increased from 298 K to 308 K is
a) 10%
b) 63%
c) 50%
d) 40%

57) The 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)
b) R = k [A][B]
c)
d) R = k [A][C]

58) What is the order of a reaction whose rate = .
a) 2
b) 1
c) -1/2
d) 3/2

59) In a reaction 2A + B C + D, if the concentration of B is kept constant and that of A is tripled, the rate of the reaction will be
a) Increased by 3 times
b) Increased by 6 times
c) Increased by 9 times
d) Constant

60) The activation energy for the forward reaction X Y is 60 kJ mole-1 and H is -20 kJ mole-1. The activation energy for the backward reaction Y X is
a)
b)
c)
d)

61) What is the half life of a radioactive substance if 87.5% of a given amount of the substance disintegrates in 40 minutes?
a) 160 min
b) 10 min
c) 20 min
d) 13 min.58sec

62) A reaction A B follows a second order kinetics. Doubling the concentration of A will increase the rate of formation of B by a factor of
a) 2
b) 4
c) 1/2
d) 1/4

63) In a reaction N2(g) + 3H2(g) 2NH3(g), the rate of appearance of NH3 is 2.5 x 10-4 moleL-1Sec-1. The rate of disappearance of H2 will be (In mole L-1Sec-1)
a)
b)
c)
d)

64) When the concentration of the reactant in a reaction AB is increased by 8 times, the rate increases only 2 times. The order of reaction would be
a) 2
b) 1/3
c) 4
d) 1/2

65) For a reaction A(g) B(g) + C(g), the half life period is 10 min. In what period of time would the concentration of A be reduced to 10% of the initial concentration?
a) 20 min
b) 33 min
c) 15 min
d) 25 min

66) Chemical reaction occurs as a result of collisions between the reacting molecules. Thus the rate of reaction is given by the
a) Total number of collisions taking place in a unit volume per sec
b) Fraction of molecules which possess energy less than the threshold energy
c) Total number of effective collisions
d) None of these

67) A first order reaction is 75% complete after 32 minutes. When was 50% of the reaction completed?
a) 16 min
b) 8 min
c) 4 min
d) 32 min

68) The rate constant is numerically the same for three reactions of the first, second and third order respectively. If the conc. of the reactant is less than 1M, which of the following is correct?
a)
b)
c)
d) None

69) The reaction between C2O42- and MnO4 is slower than that between Fe and MnO, because
a)
b)
c) Both are correct
d) Neither is correct

70) The half life of a first order reaction is 10 minutes. If the initial amount is 0.08 mole Lit-1 and the concentration at some instant is 0.01 moleLit-1, how much time has elapsed?
a) 10 min
b) 20 min
c) 30 min
d) 40 min

71) The half life of a first order reaction is 24 hours. If we start with 10 g. of the reactant, how many grams of it will remain after 96 hours?
a) 0.625 g
b) 6.25 g
c) 1.250g
d) 1.25g

72) Which of the following statements is not correct?
a) The rate of reaction depends on the physical state of the reactants (physical nature)
b) The rate of reaction depends on the activation energy of the reactants (chemical nature)
c) Fast reactions are those which have low activation energies
d) All are correct

73) If a reaction is multiplied by some constant,say n, then the value of Kp for the new reaction is Kp (new) =
a) Kp (old reaction)
b) n.Kp (old reaction)
c) Kpn (old reaction)
d)

74) At 250°C, the half life for the decomposition of N2O5 is 5.7 hours and is independent of the initial pressure of N2O5. The specific rate constant is
a) 0.693/5.7
b) 0.693 x 5.7
c) 5.7/0.693
d) None

75) In a first order reaction the a/(a-x) was found to be 8 after 10 minutes. The rate constant is
a) (2.303 x 3 log 2)/10
b) (2.303x 2 log 3)/10
c) 10 x 2.303 x 2 log 3
d) 10 x 2.303 x 3 log 2

76) For the reaction A + B Products, it is found that the order is 2 for A and 3 for B in the rate expression. When the concentration of both is doubled, the rate will increase by
a) 10
b) 6
c) 32
d) 16

77) 1f a reaction with t1/2 = 69.3 sec. has a rate constant 10-2 per sec, the order is
a) Zero
b) 1
c) 2
d) 3

78) What fraction of the reactant showing first order remains after 40 minutes if t1/2 is 20 minutes?
a) 1/4
b) 1/2
c) 1/8
d) 1/6

79) Which is false in the case of a catalyst?
a) A catalyst can initiate a reaction
b) It does not alter the position of equilibrium in a reversible reaction
c) A catalyst remains unchanged in quality and composition at the end of reaction
d) Catalysts are sometimes very specific in respect of a reaction

80) When a catalyst is introduced into a reversible reaction, the
a) Equilibrium reaction rate increases
b) Backward reaction rate increases
c) Backward reaction rate decrees
d) Equilibrium is attained quickly

81) A process, which is catalysed by one of the products, is known as
a) Auto-catalysis
b) Anti-catalysis
c) Negative catalysis
d) Acid catalysis

82) A catalyst
a) Alters the equilibrium in a reaction
b) Does not participate in the reaction but speeds it up
c) Is always in the same phase as the reactants and products
d) Participates in the reaction and provides an easier pathway for the same

83) Which of the following explains the increase in the reaction rate by a catalyst?
a) It increases the rate of the backward reaction so that the rate of the forward reaction increases
b) It provides extra energy to reacting molecules so that they may produce effective collisions
c) It provides an alternative path of lower activation energy to the reactants
d) It increases the number of collisions between the reacting molecules

84) A biological catalyst is essentially
a) An amino acid
b) An enzyme
c) A carbohydrate
d) A nitrogen molecule

85) Protons accelerate the hydrolysis of esters. This is an example of
a) A promoter
b) A heterogeneous catalyst
c) An acid catalyst
d) An auto catalyst

86) Which is correct in the case of a catalyst?
a) A catalyst is active only in solution
b) The addition of a catalyst changes the equilibrium constant
c) A catalyst speeds up the forward reaction and slows the backward reaction
d) The composition of an equilibrium mixture is not changed by a catalyst

87) Which of the following is not correct in the case of a heterogeneous catalyst?
a) The catalyst decreases the energy of activation
b) The surface of the catalyst plays an important role
c) The catalyst actually forms a compound with the reactants
d) There is no change in the energy of activation

88) A catalyst in finely divided form is most effective because
a) Less surface area is available
b) More active centres are formed
c) More energy gets stored in the catalyst
d) None

89) Which of the following is used in the Haber process for the manufacture of NH3?
a)
b) Fe + Mo
c) CuO
d) Pt

90) The catalyst used in the oxidation of SO2 giving SO3 is
a)
b)
c) Fe
d) Ni

91) For an exothermic reaction, which of the following is true?
a) Energy of reactants > energy of products
b) Energy of reactants < energy of products
c) Energy of reactants = energy of products
d) None

92) The effect of a catalyst in a chemical reaction is to change the
a) Heat of reaction
b) Equilibrium constant
c) Internal energy of the reactants
d) Activation energy required for the reaction

93) In a reversible reaction, a catalyst
a) Increases the rate of the forward reaction
b) Decreases the rate of the backward reaction
c) Increases the rate of both forward and backward reactions
d) Alters the equilibrium constant of the reaction

94) When a catalyst is added to a system, the
a) Equilibrium concentrations are increased
b) Equilibrium concentrations are unchanged
c) The rate of the forward reaction is increased and that of the backward reaction is decreased
d) Value of the equilibrium constant is decreased

95) A catalytic poison acts by
a) Chemically combining with the catalyst
b) Coagulating the catalyst
c) Getting adsorbed on the active centres on the surface of the catalyst
d) Chemical combination with anyone of the reactants

96) A negative catalyst is that
a) Which retards the rate of reaction
b) Takes the reaction in the backward direction
c) Promotes the side reaction
d) None

97) The catalyst used for the hydrogenation of vegetable oils is
a) Pt back
b)
c) Finely divided Ni
d) Copper

98) Which is true in the case of a catalyst?
a) The catalyst altered during the reaction is regenerated
b) It does not alter the equilibrium
c) It lowers the energy of activation
d) All the above

99) The efficiency of a catalyst depends on its
a) Particle size
b) Solubility
c) Molecular weight
d) None

100) The large increase in the rate of reaction due to a rise in temperature is due to the
a) Increase in collision frequency
b) Decrease in activation energy
c) Increase in the number of effective collisions
d) None


Answer :

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