 # CHEMICAL KINETICS – 1

1) For a zero-order reaction the rate constant is expressed in
a) s-1
b) mol L-1s-1
c) mol-1L-1s-1
d) mol-1Ls-1

2) The rate of a multistep reaction is determined by the
a) rate of the fastest reaction
b) rate of the slowest reaction
c) the average rates of all the steps
d) the sum of the rates of all the steps

3) In a reaction,on doubling the initial concentration of the only reactant, A, the rate of reaction increases four fold. Then the rate expression for the reaction is
a) rate=k[A]2
b) rate=k[A]0
c) rate=k[A]
d) rate=k[A]4

4) For the reaction x+y Â® products

```Expt.No         conc.of X      conc.of Y      Initial rate
1               0.1 M           0.5 M       2 * 10 -5 M/s
2               0.2 M           0.5 M       8 * 10 -5 M/s
3               0.2 M           1.0 M       8 * 10  -5 M/s
The order of the reaction is...............
a) 1
b) 2
c) 3
d) 4

5) A reaction is first order with respect to A and second order with respect to B. If the rate of  reaction is 1.6 * 10-4  mol L-1 s-1 when the conc of A is 1 M and that of B is 2 M the value of the rate constant will be
a) 4 * 10-3L2 mol -2 s-1
b) 4 * 10 -5 L 2mol 2s-1
c) 4 * 10-4L2 mol 2s-1
d) 4 * 10 -5 mol2L-2s-1

6) The kinetics of radio active decay follows
a) zero order
b) first order
c) second order
d) third order

7) Which of the following statements is false?
a) The acid hydrolysis of an ester is a first order reaction
b) The order of a reaction is an experimental quantity
c) The alkali hydrolysis of an ester is a first order reaction like acid  hydrolysis
d) The order of a reaction cannot be obtained from the stoichiometric equation for the reaction

8) For a reaction aA+bB -->cC + dD . The rate law is given by the expression
r=k[A]x [B]y
Then the order of reaction is
a) x+y
b) a+b
c) (x+y) - (a+b)
d) (x+y)(a+b)

9) The rate constant for the decomposition o N2O5 at 315 K is 4.8 * 10 -4s-1. The half life period is
a) 14.4 s
b) 144.s
c) 24 min.
d) 12 min

10) For a second order reaction AÂ®Products, a straight line graph is obtained by plotting (1/A) vs time. The slope of the curve is equal to
a) k
b) 1/2 k
c) 2k
d) k2

11) Identify the correct statements:
a) the minimum energy of collision required for 2 molecules to react is called activation
b) The collision frequency depends on the temperature
c) an activated complex is an unstable grouping of atoms that can break up to give  products
d) all the above

12) In the Arrhenius equation if we plot log k vs (1/T) then the slope is equal to
a) -Ea/2.303 RT
b) -Ea/2.303 R
c) -Ea/2.303
d) 2.303 RT/-Ea

13) The dimensions of van der Waals constant 'a' and 'b' respectively are
a) L mol -1 and L 2 atom mol
b) L2mol -1 and atm
c) L2 atm mol -2 and L mol -1
d) L atm-1 mol -2  and L mol -1

14) 1L of a gas at STP weighs 2.86g. The molar mass of the gas is
a) 1 * 22.4
b) 2.86 * 22.4
c) 22.4/2.86
d) 1/22.4

15) For the reaction  2 NO2 + F2 Â® 2NO2F. The reaction is first order with respect to both the reactants. Then the rate law is
a) k[NO2]2 [F2]
b) k[NO2] [F2]
c) k [NO2]/[F2]
d) k[NO2] [F2]2

16) For a second order reaction 2NO2 Â® 2NO + O2 at a particular temperature the rate constant is 0.5 L mol-1s-1. If the initial concentration is 0.02 mL-1 the concentration after 10 seconds will be
a) 0.002
b) 0.2
c) 0.01
d) 0.018

17) The first order decomposition of SO2CI2 has the rate constant equal to 2.2 * 10 -5 s-1. The time taken for 75 % of SO2CI2 to decompose would be
a) 3.15 * 104S
b) 3.15 * 104 hrs
c) 8.75 hrs
d) 17.5 hrs

18) The relationship between the rate constant and the slope of the curve (conc. vs time) m for a  first order reaction is equal to
a) 2.302 m
b) 2.303 /m
c) -2.303 m
d) 2.303 m2

19) For the reaction A+B Â® products```
```S.No      [A]molL-1   [B]mol L-1   initial rate mol L-1h1
1           0.1        0.24           0.032
2           0.1        0.12           0.008
3           0.2        0.12           0.016
The order of reaction with respect to A and B is respectively

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

20) The rate constant of a reaction is expressed in moles L-1 s-1. The order of reaction is
a) 1/2
b) zero
c) 1
d) 2

21) Which of the following is an example for a non- chemical process which follows first order kinetics?
a) rate of growth of bacteria culture
c) acid hydrolysis of ester
d) both a and b

22) For a first order reaction the time taken for 75% of the reaction to be completed, when compared to its half life is
a) same
b) twice
c) three times
d) four times

23) A first order reaction has a rate constant 1.1515 * 10 -1 s-1. The half life period is
a) 1080 s
b) 45.8 s
c) 60.2 s
d) 50 s

24) Colloidal gold is given by injection to act as a/an

a)  Disinfectant
b) Anticancer agent
c) Germ killer
d) Tonic to raise vitality of human system

25) Consider the preparation of SO3 according to the
reaction, 2SO2 (g) + O2(g) 2SO3
(g) ; D H = -198kJ. Which
of the following may change the value of equilibrium constant of this reaction
?
a) Adding He gas to reaction vessel
b) adding more O2 to the reaction vessel
c)  Doubling the volume of the reaction vessel
d) Increasing the temperature

26) A catalyst increases the rate of reaction by
a) Decreasing activation energy
b) Decreasing internal energy
c) Decreasing enthalpy
d) Increasing activation energy

27) Amongst the following reactions, the unimolecular reaction is
a) b) c) d) 28) The unit of rate constant of a second order chemical reaction is
a) b) c) Mole litre second
d) 29) The unit of rate constant of a first order chemical reaction is
a) Mole litre
b) c) d) 30) The expression for rate constant of a first order chemical reaction is
a) b) c) d) 31) In a reaction 2A Products, the concentration of A decreases from 0.5 mole per litre to 0.4 mole per litre
in 10 minutes. The rate of reaction during this interval is
a) b) c) d) 32) The rate constant of a first order reaction whose half life is 480 sec ,
is
a) b) c) d) 33) The conversion A B follows second
order kinetics. Doubling the concentration of A will
increase the rate of formation of B by a factor
a) 0.25
b) 2
c) 0.5
d) 4

34) The given reaction 2FeCl3 + SnCl2 +
SnCl4 is an example of a
a) First order reaction
b) Second order reaction
c) Third order reaction
d) None of these

35) If a reaction between A and B to give C shows first order kinetics in A
and second order kinetics in B, the rate equation can be written as
a) b) c) d) 36) The Arrhenius equation expressing the effect of temperature on the rate
constant of reaction is.
a) K = Ea/RT
b) c) d) 37) For a first order reaction, the half life period is independent of the
a) Initial conc.
b) Cube root of conc.
c) First power of initial conc.
d) Square root of conc.

38) The rate constant for a second order reaction is .
How long will it take a 1 M solution to be reduced to 0.5 M?
a) b) c) d) 39) For the reaction A B, the
rate law expression is rate = k [A]. Which of the following statements is
not correct ?
a) The reaction follows first order kinetics
b) c)  K is constant for the reaction at constant temperature
d) None of these

40) If the concentration of reactants is increased by X, then the rate constant k becomes
a) b) k
c) k/x
d) x/k

41) For a reaction of the type A + B Products, it is observed that doubling the concentration of A causes the reaction
rate to be four times as great, but doubling the amount of B does not affect
the rate. The rate equation is
a) Rate = k [A][B]
b) c) d) 42) The reaction 2H2O2 2H2O + O2, rate =k[H2O2] is a
a) Zero order reaction
b) First order reaction
c) Second order reaction
d) Third order reaction

43) The rate constant is given by the equation k= P. Ze Which factor should register a decrease for the reaction to proceed more rapidly?
a) T
b) Z
c) E
d) P

44) The half life period of a second order reaction is
a) Proportional to  the initial concentration of reactants
b) Independent of the initial concentration of reactants
c) Inversely proportional to the initial concentration of reactants
d) Inversely proportional to the square of the initial concentration of reactants

45) If the initial concentration of reactants in a certain reaction is doubled, the
half life period of the reaction doubles. The order of reaction is
a) Zero
b) First
c) Second
d) Third

46) The rate of reaction, A + B products is given by the equation r =k [A] [B]. If B is taken in large excess,
the order of reaction would be
a) 2
b) 1
c) 0
d) 3

47) A zero order reaction is one whose rate is independent of the
a) Temperature of the reaction
b) Concentration of the reactants
c) Concentration of the products
d) Material of the vessel in which the reaction is carried out

48) The hydrolysis of an ester in an alkaline medium is a.
a) First order reaction with molecularity 1
b) Second order reaction with molecularity 2
c) First order reaction with molecularity 2
d) Second order reaction with molecularity 1

49) @ For a reaction X + Y C
+ D; = -20kJmole-1. The activation energy of the forward reaction = 65 kJ mole-1.
The activation energy of the backward reaction is
a) 65
b) 85
c) 45
d) 40

50) The rate law for the reaction RCl + NaOH(aq) ROH + NaCl is given by rate= k[RCl] The rate of reaction will be
a) Double on doubling the concentration of NaOH
b) Halved on reducing the concentration of RCl to one half
c) Decreased on increasing the temperature of the reaction
d) Unaffected by increasing the temperature of the reaction

51) The rate of reaction between A and B increases by a factor of 100, when
the concentration w.r.t A is increased 10 fold. The order of reaction w.r.t
A is
a) 10
b) 1
c) 4
d) 2

52) The rate of a reaction can be increased in general by all the factors except
by
a) Using a catalyst
b)  Increasing temperature
c) Increasing the activation energy
d) Increasing the concentration of reactants

53) The rate of a zero order chemical reaction
a)  Increases as the reaction proceeds
b) Decreases as the reaction proceeds
c) May increase or decrease during the reaction
d) Remains constant as the reaction proceeds

54) The unit of rate constant and that of the rate of reaction are the same for
a) First order
b) Zero order
c) Second order
d) All are wrong

55) Which order of reaction obeys the relation t1/2 = 1/Ka ?
a) First order
b) Second order
c) Third order
d) Zero order

56) The reaction, CH3COONa
+ C2H5OH is
a) Second order
b) Bimolecular
c) Both
d) None

57) The half life period of a reaction
a) Increases with an increase in temperature
b) Decreases with an increase in temperature
c) Remains unaffected
d) None

58) The temperature coefficient of a reaction is:
a) The rate constant at a fixed temperature
b) The ratio of rate constants at two temperatures
c) d) None

59) The half life period for a zero order reaction is
a) b) c) d) 60) The unit of rate constant depends on the
a) Order of reaction
b) Molecularity of the reaction
c) Concentration terms
d) Number of reactants

61) The hydrolysis of ethyl acetate, CH3COOC2H5+ H2O CH3COOH +C2H5OH is:
a) First order
b) Second order
c) Third order
d) Zero order

62) A large increase in the rate of reaction for a rise in temperature is
due to the
a) Increase in the number of collisions
b) Increase in the number of activated molecules
c) Lowering of activation energy
d) Shortening of the  mean free path

63) According to the collision theory of reaction rates
a)  Every collision between reactant molecules leads to chemical reaction
b) The rate of reaction is proportional to the velocity of molecules
c) All reactions which occur in te gaseous phase are zero order reactions
d) the rate of reaction is directly proportional to the collision frequency

64) According to the collision theory, the rate of reaction depends on the
a)  No. of collisions
b) No. of effective collisions
c) Concentration of reactants
d) Number of collisions between reactants and products

65) For the reaction, H2(g) + Br2(g)  2HBr(g), the
reaction rate = k[H2] [Br2]1/2. Which statement is true
a) The reaction is of second order
b) Molecularity of the reaction is 3/2
c) d) Molecularity of the reaction is 2

66) The collision theory satisfactorily explains the
a) First order reaction
b) Zero order reaction
c) Bimolecular reaction
d) Any order reaction

67) A zero order reaction is one
a) In which reactants do not react
b)  In which one of the reactants is in large excess
c) Whose rate does not change with time
d) Whose rate increases with time

68) A reaction proceeds in three stages. The first stage is slow and involves
two molecules of reactants. The second and third stages are fast.The overall
order of the reaction is
a) First order
b) Second order
c) Third order
d) Zero order

69) The rate expression of a chemical change is dx/dt = k [A]2[B][C] .
The order of the reaction is
a) 2
b) 3
c) 1
d) Zero

70)```

The rate of reaction A + B + C Products is given by

Rate = = k [A]1/2[B]1/2[C]1/4

The order of reaction is

```a) 1
b) 2
c) d) 5/4

71) The reaction 2A B + C follows zero order kinetics. The differential rate equation for the reaction
is
a) b) c) d) 72) Which statement is true?
a) Endothermic reactions have higher activation energies than exothermic reactions
b) The specific rate constant for a reaction is independent of the concentration of the reacting species
c) There is a single rate determining step in any reaction mechanism
d) None of the above

73) Which will lead to a change in the rate constant k of a reaction?
a) A change in the pressure
b) A change in the temperature
c) A change in the volume of the reaction vessel
d) All

74) For a reaction, the rate of reaction was found to increase about 1.8 times
when the temperature was increased by 10Â°C. The increase in rate is due to
a) An increase in the number of active molecules
b) an increase in the activation energy of the reactants
c) A decrease in the activation energy of the reactants
d) an increase in the number of collisions between the reacting molecules

75) For a given reaction the half life period was found to be directly proportional
to the initial concentration of the reactant. The order of reaction is
a) 0
b) 1
c) 2
d) 3

76) The rate constant k of
a reaction has been found to be double the rate constant k2 of another reaction.
The relationship between the corresponding activation energies of the two reactions
(E and E2) can be
a) b) c) d) None

77) In a reaction, the threshold energy is equal to
a) Activation energy + normal energy of the reactants
b) Activation energy - normal energy of the reactants
c) Activation energy
d) The normal energy of the reactants

78) The inversion of cane sugar into glucose and fructose is
a) First order
b) Second order
c) Third order
d) Zero order

79) The minimum energy required by molecules to enter into chemical reaction is
called
a) Kinetic energy
b) Potential energy
c) Threshold energy
d) Activation energy

80) The rate of reaction can be kept constant by
a) Stirring the compounds
b) Keeping the temperature constant
c) Both (a) and (b)
d) None

81)  For a reaction for which the activation energies of forward and backward
reactions are equal,

a) b) c) The order is zero
d) There is no need of catalyst

82) On increasing the temperature by 10 K in the case of a slow reaction, the
a) Number of collisions is doubled
b) Value of the rate constant increases
c) Energy of activation increases
d) None

83) The activation energy of a reaction is
a) The energy released during the reaction
b) The energy involved when an activation complex is formed
c) The minimum amount of energy required to overcome the potential barrier of reaction
d) The energy needed to form 1 mole of the product

84) @ The number of moles of a substance present in one litre volume is called.	 the
a) Activity
b) Molar concentration
c) Molal concentration
d) None

85) The number of molecules of the reactants taking part in a single step of
the reaction tells us the
a) Molecularity of the reaction
b) Mechanism of the reaction
c) Order of reaction
d) All

86) Which statement about the molecularity of reaction is not correct?
a) It is the number of molecules of the reactants taking part in a single step
of reaction
b) It is calculated from the reaction mechanism
c) It may be either a whole number or fractional
d)  None of the above choices

87) According to the Arrhenius equation a straight line is obtained by plotting
the log of the rate constant of a chemical reaction (log k) against
a) T
b) Log T
c) 1/T
d)  Log 1/T

88) For producing effective collisions the colliding molecules must have
a) A certain minimum amount of energy
b) An energy smaller than the threshold energy
c) An iImproper orientation
d) A proper orientation and an energy equal or greater than the threshold energy

89)```

A reaction follows the mechanism

A2 A + A (Fast)
A + B2 AB + B (Slow)
A + B AB (Fast)
The order of the overall reaction is.

```a) 1
b) 2
c) 1.5
d) Zero

90) The burning of coal can be represented as
C(s) + O2 (g) CO2(g). The rate of this reaction increases by
a) Decreasing the concentration of oxygen
b) Powdering the lumps of coal
c) Decreasing the temperature
d) Providing an  inert atmosphere for burning

91)```

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]

92) The decomposition of N2O5 occurs as and follows first order kinetics. Hence the rate of formation of NO2 is
a) Twice that for the disappearance of N2O5
b) Half that for the disappearance of N2O5
c) The same for the disappearance of N2O5
d) Independent of the disappearance of N2O5

93) Which does not influence the rate of reaction?
a) The nature of reactants
b) The concentration of reactants
c) the temperature
d) the molecularity

94) If a is the initial concentration, then the time required to complete half of the reaction
for the nth order is inversely proportional to
a) b) c) d) 95) The rate of reaction
a) Decreases with time
b) Decreases with decreasing concentration of reactants
c) Decreases with increase in time and decrease in the concentration of the reactants
d) None

96) In a reaction, the rate expression is, rate = K [A] [B]2/3.
The order of reaction is
a) 1
b) 2
c)  5/3
d) Zero

97) The term - dc/dt in a rate equation refers to
a) The concentration of a reactant
b) The decrease in concentration  of the reactant with time
c) The rate constant of the reaction
d) The order of the reaction

98) An increase in the rate of a reaction on a rise in temperature is due
to the
a)  Increase in the collision frequency
b) Shortening of the mean free path
c) Increase in the number of activated molecules
d) All	 the above

99) Which statement is correct?
a) Reactions with low activation energy are usually exothermic
b) The rate law sometimes enables us to deduce the mechanism of a reaction
c) The rate law for a reaction is an algebraic expression relating the forward reaction rate to product concentration
d) Increase in the total pressure of a gas phase reaction increases the fraction of collisions effective in producing reactions

100) Zero order reaction means
a) One reactant will have a higher concentration in it
b) Reactants do not take part in it
c) The rate of reaction is  constant
d) The reactant concentration does not change with time
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```Answer :

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