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Rate of a reaction
1. The rate of a chemical reaction [MP PMT 1973; CPMT 1982] (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 2. The rate of a reaction that not involve gases is not dependent on [CPMT 1988; AFMC 1995] (a) Pressure (b) Temperature (c) Concentration (d) Catalyst 9. The rate at which a substance reacts depends on its [MP PMT 1987; BHU 1999; KCET 2005] (a) Atomic weight (b) Equivalent weight (c) Molecular weight (d) Active mass 10. The rate law for the reaction RCl NaOH ( aq ) ROH NaCl is given by Rate K 1 [ RCl ]. The rate of the reaction will be [IIT 1988] (a) Doubled on doubling the concentration of sodium hydroxide (b) Halved on reducing the concentration of alkyl halide to one half (c) Decreased on increasing the temperature of the reaction (d) Unaffected by increasing the temperature of the reaction 11. If doubling the concentration of a reactant A' increases the rate 4 times and tripling the concentration ofA' increases the rate 9 times, the rate is proportional to [AIIMS 1991] (a) Concentration of A' (b) Square of concentration ofA' (c) Under root of the concentration of A' (d) Cube of concentration ofA' 12. The rate of chemical reaction at constant temperature is proportional to (a) The amount of products formed (b) The product of masses of the reactants (c) The product of the molar concentration of the reactants (d) The mean free path of the reaction 13. The concentration of a reactant decreases from 0.2 M to 0.1 M in 10 minutes. The rate of the reaction is (a) 0.01 M (b) 10 ^2 (c) 0.01 mol dm ^3 min ^1 (d) 1 mol dm ^3 min ^1 14. When a reaction is progressing (a) The rate of the reaction goes on increasing (b) The concentration of the products goes on decreasing (c) The concentration of the reactants goes on decreasing
(d) The reaction rate always remains constant
15. In a catalytic conversion of N 2 to NH 3 by Haber's process, the rate of reaction was expressed as change in the concentration of ammonia per time is 40 10 ^3 mollitre ^1 s ^1. If there are no side reaction, the rate of the reaction as expressed in terms of hydrogen is (in mol litre ^1 s ^1 ) (a) 60 10 ^3 (b) 20 10 ^3 (c) 1.200 (d) 10. 3 10 ^3 16. If the concentration of the reactants is increased, the rate of reaction [MP PMT 1989] (a) Remains unaffected (b) Increases (c) Decreases (d) May increase or decrease 17. Time required for completion of ionic reactions in comparison to molecular reactions is (a) Maximum (b) Minimum (c) Equal (d) None 18. For reaction (^2) A B products, the active mass of B is kept constant and that of A is doubled. The rate of reaction will then [MP PET 1993 (a) Increase 2 times (b) Increase 4 times (c) Decrease 2 times (d) Decrease 4 times 19. In a reaction 2 A B A 2 B , the reactant A will disappear at [MP PET 1993] (a) Half the rate that B will decrease (b) The same rate that B will decrease (c) Twice the rate that B will decrease (d) The same rate that A 2 B will form 20. The rate of a gaseous reaction is given by the expression (^) K [ A ][ B ]. If the volume of the reaction vessel is suddenly reduced to 1/4th of the initial volume, the reaction rate relating to original rate will be [Roorkee 1992] (a) 1/10 (b) 1/ (c) 8 (d) 16 21. A catalyst increases the rate of reaction because it [EAMCET 1992] (a) Increases the activation energy (b) Decreases the energy barrier for reaction (c) Decreases the collision diameter (d) Increases the temperature coefficient 22. For the reaction N (^) 2 ( g ) 3 H 2 ( g ) 2 NH 3 ( g ) under certain conditions of temperature and partial pressure of the reactants, the rate of formation of NH 3 is 0. 001 kg h ^1. The rate of conversion of H 2 under the same conditions is [IIT 1994] (a) 1. 82 10 ^4 kg / hr (b) 0. 0015 kg / hr (c) 1. 52 104 kg / hr (d) 1. 82 10 ^14 kg / hr 23. In the reaction 2 A B A 2 B , if the concentration of A is doubled and of B is halved, then the rate of the reaction will [MP PET 1994 (a) Increase by four times (b)Decrease by two times (c) Increase by two times (d) Remain the same
24. The term
dt
dc in a rate equation refers to the
[MP PMT 1996] (a) Concentration of the reactant (b) Decrease in concentration of the reactant with time (c) Increase in concentration of the reactant with time (d) Velocity constant of the reaction
25. The rate of a reaction depends upon the [Pb. PMT 1999] (a) Volume (b) Force (c) Pressure (d) Concentration of reactant 26. For a given reaction 3 A B C D the rate of reaction can be represented by [DCE 2000] (a) dt
dD dt
dC dt
dB dt
d [ A ] [] [ ] [ ] 3
^1
(b) KAm^ Bn dt
dC dt
d [ A ] [] [ ][] 3
^1
(c) KAn^ Bm dt
dC dt
d [ A ] [ ] [ ][ ] 3
^1
(d) None of these
27. For the reaction N (^) 2 3 H 2 2 NH 3
if 2 10 ,
[ 3 ] 4 1 1
moll s t
NH
the value of t
H
[ 2 ]
would be [MP PMT 2000] (a) 1 10 ^4 moll ^1 s ^1 (b) 3 10 ^4 moll ^1 s ^1 (c) 4 10 ^4 moll ^1 s ^1 (d) 6 10 ^4 moll ^1 s ^1
28. A gaseous hypothetical chemical equation 2 A ⇌ 4 B C is carried out in a closed vessel. The concentration of B is found to increase by 5 10 ^3 moll ^1 in 10 second. The rate of appearance of B is [AFMC 2001] (a) 5 10 ^4 moll ^1 sec ^1 (b) 5 10 ^5 moll ^1 sec ^1 (c) 6 ^10 ^5 moll ^1 sec^1 (d)^4 ^10 ^4 moll ^1 sec^1 29. The rate of a chemical reaction depends upon [AFMC 2002] (a) Time (b) Pressure (c) Concentration (d) All of these 30. The rate of disappearance of SO 2 in the reaction
2 SO (^) 2 O 2 2 SO 3 is^1.^2810 g^ / sec ^3 then the rate of formation of SO 3 is [JIPMER 2002] (a) 0. 64 10 ^3 g / sec (b) 0. 80 10 ^3 g / sec (c) 1. 28 10 ^3 g / sec (d) 1. 60 10 ^3 g / sec
31. When the concentration of A in the reaction
A B^ ⇌^ AB is doubled, the rate of reaction will be^ [MP PMT 2002] (a) Doubled (b) Decreased by half (c) Unchanged (d) Increased by four times
32. The velocity of the chemical reaction doubles every 10 oC rise of temperature. If the temperature is raised by 50 oC , the velocity of the reaction increases to about (a) 32 times (b) 16 times (c) 20 times (d) 50 times 33. An increase in temperature by 10 oC , generally increases the rate of a reaction by
(a) 2 times (b) 10 times (c) 9 times (d) 100 times
34. The temperature coefficient for reaction in which food deteriorates is 2. Then food deteriorates ...... times as rapidly at 25 oC as it does at^5 oC (a) Two (b) Four (c) Six (d) Twenty 35. The rate of a reaction is doubled for every 10 o rise in temperature. The increase in reaction rate as a result of temperature rise from 10 o to 100 o is [KCET 1993; Kerala PET 2002; MP PET 2003] (a) 112 (b) 512 (c) 400 (d) 614 36. A catalyst increases the rate of a chemical reaction by [MNR 1988; CPMT 1999; Pb. PMT 2000] (a) Increasing the activation energy (b) Decreasing the activation energy (c) Reacting with reactants (d) Reacting with products 37. Velocity constant of a reaction at 290 K was found to be 3.^2 ^10 ^3. At 310 K it will be about [KCET 1989, 91] (a) 1. 28 10 ^2 (b) 9. 6 10 ^3 (c) 6. 4 10 ^3 (d) 3. 2 10 ^4 38. The temperature coefficient of a reaction is (a) Specific reaction rate at 25 oC (b) Rate of the reaction at 100 oC (c) Ratio of the rate constants at temperatures 35 oC and 25 oC (d) Ratio of the rate constants at two temperatures differing by 1 oC 39. The main function of a catalyst in speeding up a reaction is (a) To increase the rate of the forward reaction (b) To change the reaction path so as to decrease the energy of activation for the reaction (c) To reduce the temperature at which the reaction can occur (d) To increase the energy of the molecules of the reactants 40. The rate of a reaction [CPMT 1973] (a) Increases with increase in temperature (b) Decreases with increase in temperature (c) Does not depend on temperature (d) Does not depend on concentration 41. Which of the following statements is false in relation to enzyme [MP PMT 2003] (a) pH affects their functioning (b) Temperature affects their functioning (c) They always increase activation energy (d) Their reactions are specific 42. A reaction is catalysed by ‘ X ’. Here ‘ X ’ [MP PMT 2003] (a) Decreases the rate constant of reaction (b) Does not affect the equilibrium constant of reaction (c) Decreases the enthalpy of reaction (d) Decreases the activation energy 43. Which reaction characteristics are changing by the addition of a catalyst to a reaction at constant temperature
(b) Change of temperature (c) Change in the concentration of the product (d) None of the above
12. Point out the wrong statement :
For a first order reaction (a) Time for half-change ( t (^1) / 2 ) is independent of initial concentration (b) Change in the concentration unit does not change the rate constant( K ) (c) Time for half-change rate constant 0. 693 (d) The unit of K is mole ^1 min ^1
13. The rate constant of a reaction depends on [CPMT 1989; DPMT 2001] (a) Temperature (b) Mass (c) Weight (d) Time 14. In a first order reaction the concentration of reactant decreases from 800 mol / dm^3 to 50 mol / dm^3 is 2 102 sec. The rate constant of reaction in sec ^1 is [IIT-JEE (Screening) 2003] (a) 2 104 (b) 3. 45 10 ^5 (c) 1.^386 ^10 ^2 (d)^2 ^10 ^4 15. For a reaction A B , the rate of reaction quadrupled when the concentration of A is doubled. The rate expression of the reaction is r K ( A ) n. when the value of n is (a) 1 (b) 0 (c) 3 (d) 2 16. The velocity constant of a reaction is K. Which of the following statements is not true regarding K (a) K is a constant for a reaction at a given temperature
(b) The value of K changes when the temperature changes
(c) K is the velocity of the reaction at unit concentrations of the reactant (d) K is a constant for all reactions
17. For the following reaction scheme (homogeneous), the rate constant has units : A B K C^ [MP PET 1999] (a) sec ^1 mole (b) sec ^1
(c) sec ^1 litremole ^1 (d) sec
18. Which of the following oxides of nitrogen will be the most stable one [NCERT 1978] (a) 2 NO 2 ( g )⇌ N 2 ( g ) 2 O 2 ( g ); K 6. 7 1016 moll ^1 (b) 2 NO ( g )⇌ N 2 ( g ) O 2 ( g ); K 2. 2 1030 moll ^1 (c) 2 N 2 O 5 ( g )⇌ 2 N 2 ( g ) 5 O 2 ( g ); K 1. 2 1034 moll ^5 (d) 2 N 2 O ( g )⇌ 2 N 2 ( g ) O 2 ( g ); K 3. 5 1033 mollitre ^1 19. The rate of reaction is determined by slow step reaction. The step is called (a) Reaction rate (b) Activation step (c) Rate determining step (d) None of the above 20. The rate of the reaction CCl (^) 3 CHO NO CHCl 3 NO CO is given by Rate K [ CCl 3 CHO ][ NO ]^. If concentration is expressed in moles/litre, the units of K are [MP PET 1993] (a) litre^2^ mole ^2 sec^ ^1 (b) mole^ litre ^1 sec^ ^1 (c) litre mole ^1 sec ^1 (d) sec ^1 21. Rate constant for a reaction H (^) 2 I 2 2 HI is 49, then rate constant for reaction 2 HI H 2 I 2 is [Bihar MEE 1997] (a) 7 (b) 1/ (c) 49 (d) 21 (e) 63 22. The reaction
() 2
1 N 2 (^) O 5 (in CCl 4 solution) 2 NO 2 (solution) O 2 g
is of first order in N 2 O 5 with rate constant
- 2 10 ^1 s ^1. What is the value of rate of reaction when [ N 2 O 5 ] 1. 25 molel ^1 [AFMC 1998] (a) 7. 75 10 ^1 molel ^1 s ^1 (b) 6. 35 10 ^3 molel ^1 s ^1 (c) 5. 15 10 ^5 molel ^1 s ^1 (d) 3. 85 10 ^1 molel ^1 s ^1
23. A reaction that is of the first order with respect to reactant A has a rate constant 6 min^1. If we start with [ A ] 0. 5 moll ^1 , when would [ A ]reach the value 0.05 mol l ^1 [KCET 2000] (a) 0.384 min (b) 0.15 min (c) 3 min (d) 3.84 min 24. The rate constant for the reaction, 2 N (^) 2 O 5 4 NO 2 O 2 is 3 10 ^5 sec^1. If the rate is 2. 40 10 ^5 mollitre -1sec^1. Then the concentration of N 2 O 5 (in mol litre -^1 ) is [IIT Screening 2000] (a) 1.4 (b) 1. (c) 0.04 (d) 0. 25. For the reaction 2 N (^) 2 O 5 4 NO 2 O 2 rate of reaction and rate constant are 1. 02 10 ^4 and 3. 4 10 ^5 sec^1 respectively. The concentration of N 2 O 5 at that time will be [BHU 2001] (a) 1. 732 (b) 3 (c) 1.^02 ^10 ^4 (d)^3.^4 ^105 26. The rate law of the reaction 2 N (^) 2 O 5 4 NO 2 O 2 is [MP PET 2002] (a) r K [ N 2 O 5 ] (b) r K [ N 2 O 5 ]^2 (c) r^ K [^ N 2 O 5 ]^0 (d) r^ K [^ NO 2 ] 4 [ O 2 ] 27. If R K [ NO ]^2 [ O 2 ],rate constant may be increased by [BHU 2003] (a) Increasing temperature (b) Decreasing temperature (c) Increasing concentration of O 2 (d) Increasing concentration of NO 28. The value of rate constant A B products depends on [BHU 2003] (a) Concentration of A and B
(b) Pressure (c) Temperature (d) All of these
29. The rate constant of a reaction depends upon [BHU 2004] (a) Extent of reaction (b) Time of reaction (c) Temperature of the system (d) Concentration of the system 30. The rate equation for the reaction 2 A B C is found to be: rate k [ A ][ B ]. The correct statement in relation to this reaction is that the [AIEEE 2004] (a) Rate of formation of C is twice the rate of disappearance of A (b) t 1 / 2 is a constant (c) Unit of k must be s ^1 (d) Value of k is independent of the initial concentrations of A and B 31. The specific rate constant of a first order reaction depends on the [IIT 1981, 83; DPMT 1991; Bihar MEE 1995; KCET 1998] (a) Concentration of the reactants (b) Concentration of the products (c) Time of reaction (d) Temperature of reaction 32. If the concentration is expressed in moles per litre, the unit of the rate constant for a first order reaction is [MNR 1986; MP PET 1994, 2000, 01;Bihar MEE 1996; CPMT 1997; MP PMT 1995, 96, 99;AFMC 2002] (a) mole litre ^1 sec ^1 (b) mole litre ^1 (c) sec ^1 (d) mole ^1 litre ^1 sec ^1 33. The dimension of rate constant of a second order reaction involves [NCERT 1982] (a) Neither time nor concentration (b) Only time (c) Time and concentration (d) Time and square of concentration 34. The unit of rate constant of second order reaction is usually expressed as [NCERT 1983, 84; MNR 1983; MP PMT 1994, 99] (a) mole litre sec ^1 (b) mole ^1 litre ^1 sec ^1 (c) mole litre ^1 sec ^1 (d) mole ^1 litre sec ^1 35. A zero order reaction is one whose rate is independent of [NCERT 1981] (a) Temperature of the reaction (b) The concentrations of the reactants (c) The concentration of the products (d) The material of the vessel in which the reaction is carried out 36. The unit of rate constant for a zero order reaction is [NCERT 1981; MP PMT 2000; RPET 2000] (a) litre sec ^1 (b) litre mole ^1 sec ^1 (c) mole litre ^1 sec ^1 (d) mole sec ^1 37. Which of the following rate laws has an overall order of 0.5 for reaction involving substances x , y and z [AIIMS 1983] (a) Rate K ( Cx )( Cy )( Cz )
(b) Rate K ( C (^) x )^0.^5 ( Cy )^0.^5 ( Cz )^0.^5 (c) Rate K ( C (^) x )^1.^5 ( Cy )^1 ( Cz )^0 (d) Rate K ( C (^) x )( Cz ) n /( Cy )^2
38. The rates of a certain reaction ( dc/dt ) at different times are as follows Time Rate ( mole litre –^1 sec –^1 ) 0 2. 8 10 ^2 (^102). 78 10 ^2 20 2. 81 10 ^2 30 2. 79 10 ^2 The reaction is [NCERT 1978] (a) Zero order (b) First order (c) Second order (d) Third order 39. For a chemical reaction (^) A B it is found that the rate of reaction doubles, when the concentration of A is increased four times. The order in A for this reaction is [NCERT 1979; AIIMS 1997; J & K CET 2005] (a) Two (b) One (c) Half (d) Zero 40. The following data are for the decomposition of ammonium nitrate in aqueous solution Volume of N 2 in cc Time (minutes) 6.25 10 9.50 15 11.42 20 13. 65 25 35.05 Finally The order of the reaction is [NCERT 1980 (a) Zero (b) One (c) Two (d) Three 41. The hydrolysis of ethyl acetate is a reaction of [MP PMT 1987] CH COOEt HO H ^ CHCOOH EtOH
3 2 3 (a) First order (b) Second order (c) Third order (d) Zero order
42. The rate of reaction between A and B increases by a factor of 100, when the concentration of A is increased 10 folds. The order of reaction with respect to A is [CPMT 1985] (a) 10 (b) 1 (c) 4 (d) 2 43. Which of the following is a first order reaction [MP PMT 1987] (a) NH (^) 4 NO 2 N 2 2 H 2 O (b) 2 HI H 2 (^) I 2 (c) 2 NO (^) 2 2 NO O 2 (d) 2 NO O 2 2 NO 2 44. The inversion of cane sugar is represented by C 12 (^) H 22 O 11 H 2 O C 6 H 12 O 6 C 6 H 12 O 6 It is a reaction of [AFMC 1982; MP PMT 1993; RPET 2000] (a) Second order (b) Unimolecular (c) Pseudo unimolecular (d) None of the three
63. The velocity constant of first order reaction is expressed in the units (a) Concentration per unit time (b) Time per unit concentration (c) Per unit time (d) Unit time per unit concentration 64. For reation, A B products, it is found that the rate of the reaction is proportional to the concentration of A , but it is independent of the concentration of B, then (a) The order of the reaction 2 and molecularity 1 (b) Molecularity of the reaction is 2 but order is 1 (c) Order is 2 and molecularity is 2 (d) Order of the reaction is 2 but molecularity is 0 65. For a zero order reaction (a) The concentration of the reactant does not change during the reaction (b) The concentration change only when the temperature changes (c) The rate remains constant throughout (d) The rate of the reaction is proportional to the concentration 66. If ‘ a’ is the initial concentration and ‘ n’ is the order of the reaction and the half life period is ‘ T’ , then [MH CET 2000] (a) T an ^1 (b) T an (c) n a
T 1 (d) 1 1 T (^) an
67. In presence of HCl , sucrose gets hydrolysed into glucose and fructose. The concentration of sucrose was found to reduce form 0.4 M to 0.2 M in 1 hour and 0.1 M in 2 hours. The order of the reaction is (a) Zero (b) One (c) Two (d) None of these 68. The time of half change of a first order reaction in ....... initial concentration (a) Proportional to (b) Inversely proportional to (c) Independent of (d) Equal to 69. Half life period of a first order reaction is 138. minutes. The velocity constant of the reaction is (a) 0. 05 min^1 (b) 0. 00005 min^1 (c) 0. 005 min^1 (d) 200 min^1 70. An example of a pseudo – unimolecular reaction is (a) Dissociation of hydrogen iodide (b) Hydrolysis of methyl acetate in dilute solution (c) Dissociation of phosphorus pentachloride (d) Decomposition of hydrogen peroxide 71. About half life period of a first order reaction, which one of the following statements is generally false (a) It is independent of initial concentration (b) It is independent of temperature (c) It decreases with the introduction of a catalyst
(d) It increases with increase of temperature
72. Decomposition of nitrogen pentoxide is known to be a first order reaction 75 percent of the oxide had decomposed in the first 24 minutes. At the end of an hour, after the start of the reaction, the amount of oxide left will be (a) Nil (b) About 1% (c) About 2% (d) About 3% 73. A reaction 2 A products is found to follow zero oder kinetics, then
(a) k [ A ]^2 dt
dx^ (b) k [ A ]^0 dt
dx (^)
(c) k [ A ] dt
dx (d) k [ 2 A ] dt
dx
74. The alkaline hydrolysis of ethyl acetate is represented by the equation CH (^) 3 COOC 2 H 5 NaOH CH 3 COONa C 2 H 5 OH Experimentally it is found that for this reaction
k [ CH 3 COOC 2 H 5 ][ NaOH ] dt
dx (^)
Then the reaction is [JIPMER 1999] (a) Bimolecular and of first order (b) Bimolecular and of second order (c) Pseudo–bimolecular (d) Pseudo–unimolecular
75. For the reaction (^2) HI ⇌ (^) H 2 (^) I 2 , the rate of the reaction is proportional to [ HI ]^2. This means that the reaction is [AMU 1985; MP PET 2000] (a) Unimolecular (b) Bimolecular (c) Of first order (d) Of second order 76. Inversion of sucrose is [AMU 1988; MP PET 2000] (a) Zero order reaction (b) First order reaction (c) Second order reaction (d)Third order reaction 77. The one which is unimolecular reaction is [MP PMT 1999; UPSEAT 2001]
(a) 2 HI H 2 I 2 (b) 2 5 2 4 2 2
N O NO ^1 O
(c) H (^) 2 Cl 2 2 HCl (d) PCl 3 (^) Cl 2 PCl 5
78. Integrated velocity equation for first order reaction is (a) [ A^ ] o^ ^ [ A ] e Kt (b) K^^ [ A^ ] o e A / t
(c) []
- 303 log[ ] A
Kt Ao (d) Kt A
A (^) o (^) 2. 303 [ ]
log []
79. If the surface area of the reactants increases, then order of the reaction (a) Increases (b) Decreases (c) Remain constant (d) Sometimes increases and sometimes dereases 80. Half life period (^) t 1 / 2 for first order reaction is
(a) K (b) K
- 303 log 2
(c) K
2.^303 log^2 (d) K
9
81. Molecularity of reaction of inversion of sugar is
(a) 3 (b) 2 (c) 1 (d) 0
82. For any reaction, if we plot a graph between time ‘ t ’ and log( a x ), a simple line is obtained. The order of reaction is (a) Zero (b) One (c) Two (d) Three 83. Value of velocity constant for first order reaction is 3. 46 10 ^3 min^1 , the time for half change is (a) 100 minutes (b) 400 minutes (c) 200 minutes (d) 346 minutes 84. The unit of the velocity constant in case of zero order reaction is [CPMT 1994] (a) Conc. time ^1 (b) Conc .^1 time (c) Conc. ^1 time ^1 (d) Conc. ( time )^2 85. For the reaction H (^) 2 ( g ) Br 2 ( g ) 2 HBr ( g ), the
experimental data suggest, rate K [ H 2 ][ Br 2 ]^1 /^2. The molecularity and order of the reaction are respectively [CPMT 1988; MP PET 1993]
(a) 2
2 ,^3 (b) 2
,^3 2
3
(c) 1, 1 (d) 2
1 ,^1
86. The incorrect order indicated against the rate of reaction (^) A B K C is [BHU 1990] Rate Order
(a) [ ] [ ] KA dt
d C 1
(b) [^ ] K [ A ][ B ] dt
d^ C 2
(c) [^ ] K [ A ][ B ]^0 dt
d^ A 2
(d) [^ ] K [ A ] dt
dA 1
87. Which of the following statements regarding the molecularity of a reaction is wrong [CBSE PMT 1989] (a) It is the number of molecules of the reactants taking part in a single step chemical reaction (b) It is calculated from the reaction mechanism (c) It may be either a whole number or fractional (d) It depends on the rate determining step in the reaction 88. Diazonium salt decomposes as
C 6 (^) H 5 N 2 Cl C 6 H 5 Cl N 2
At 0 oC , the evolution of N 2 becomes two times faster when the initial concentration of the salt is doubled. Therefore, it is [MNR 1994; UPSEAT 2002] (a) A first order reaction (b) A second order reaction (c) Independent of the initial concentration of the salt (d) A zero order reaction
89. In the reaction A B Products, if B is taken in excess, then it is an example of [EAMCET 1992]
(a) Second order reaction (b) Zero order reaction (c) Pseudounimolecular reaction (d) First order reaction
90. The half life of a first order reaction is 69. 35 sec. The value of the rate constant of the reaction is [CBSE PMT 1990] (a) 1. 0 s ^1 (b) 0. 1 s ^1 (c) 0. 01 s ^1 (d) 0. 001 s ^1 91. The half life for the reaction N 2 O 5 ⇌ 2 2 2
1 2 NO O
in (^24) hrs at 30 oC. Starting with (^10) g of (^) N 2 O 5 how many grams of N 2 O 5 will remain after a period of 96 hours [KCET 1992] (a) 1. 25 g (b) 0. 63 g (c) (^1). 77 g (d) 0. 5 g
92. The half life of a first order reaction is 10 minutes. If initial amount is 0. 08 mol / litre and concentration at some instant is 0. 01 mol / litre , then t [Roorkee 1990] (a) 10 minutes (b) 30 minutes (c) 20 minutes (d) 40 minutes 93. Half life period of second order reaction is [MP PMT 1994] (a) Proportional to the initial concentration of reactants (b) Independent of the initial concentration of reactants (c) Inversely proportional to initial concentration of reactants (d) Inversely proportional to square of initial concentration of reactants 94. The reaction 2 H 2 (^) O 2 2 H 2 O O 2 is a [Manipal MEE 1995] (a) Zero order reaction (b) First order reaction (c) Second order reaction (d)Third order reaction 95. In a reaction involving hydrolysis of an organic chloride in presence of large excess of water RCl H 2 O ROH HCl [MP PET 1995] (a) Molecularity is 2, order of reaction is also 2 (b) Molecularity is 2, order of reaction is 1 (c) Molecularity is 1, order of reaction is 2 (d) Molecularity is 1, order of reaction is also 1 96. The thermal decomposition of a compound is of first order. If a sample of the compound decomposes 50% in 120 minutes, in what time will it undergo 90% decomposition [MP PET 1996] (a) Nearly 240 minutes (b) Nearly 480 minutes (c) Nearly 450 minutes (d) Nearly 400 minutes 97. The order of a reaction with rate equals 3 / 2 1 / 2 kCA C B is [MP PET 1996, 2001] (a) 2 (b) 1
(c) 2
1 (d) 2
3
116. Certain bimolecular reactions which follow the first order kinetics are called [KCET (Med.) 1999] (a) First order reactions (b) Unimolecular reactions (c) Bimolecular reactions (d) Pseudounimolecular reactions 117. The rate law of the reaction A 2 B Product is
given by [^ ] k [ B^2 ] dt
d^ dB . If A is taken in excess, the order of the reaction will be [AMU (Engg.) 1999] (a) 1 (b) 2 (c) 3 (d) 0
118. For a first order reaction A product, the rate of reaction at [ A ] 0. 2 moll ^1 is 1. 0 10 ^2 moll ^1 min^1. The half life period for the reaction is [Roorkee 1999] (a) 832 s (b) 440 s (c) 416 s (d) 13.86 s 119. For the reaction A B products, doubling the concentration of A the rate of the reaction is doubled, but on doubling the concentration of B rate remains unaltered. The over all order of the reaction is [JIPMER 1999] (a) 1 (b) 0 (c) 2 (d) 3 120. Which among the following is a false statement [KCET 1999] (a) Half life of a third order reaction is inversely proportional to the square of initial concentration of the reactant. (b) Molecularity of a reaction may be zero or fractional
(c) For a first order reaction K t
- 693 1 / 2
(d) Rate of zero order reaction is independent of initial concentration of reactant
121. After how many seconds will the concentration of the reactants in a first order reaction be halved, if the decay constant is 1.155 10 -3^ sec^1 [CBSE PMT 2000] (a) 100 sec (b) 200 sec (c) 400 sec (d) 600 sec 122. What is the order of a reaction which has a rate expression rate K [ A ]^3 /^2 [ B ]^1 [DCE 2000] (a) 3/2 (b) 1/ (c) 0 (d) None of these 123. Which of the following expression is correct for first order reaction? ( CO ) refers to initial concentration of reactant [DCE 2000] (a) t (^) 1 / 2 CO (b) t 1 / 2 CO^ ^1
(c) t 1 / 2 CO ^2 (d) t 1 (^) / 2 CO^0
124. For a reaction 2 NO ( g ) Cl 2 ( g )⇌ 2 NOCl ( g ). When
concentration of Cl 2 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 [MP PMT 2000]
(a) 1 (b) 2 (c) 3 (d) 4
125. The rate constant for a second order reaction is 8 10 ^5 M ^1 min ^1.^ How^ long^ will^ it^ take^ a^1 M solution to be reduced to 0.5 M [MH CET 2001] (a) 8 10 ^5 min (b) 8. 665 103 min (c) 4 10 ^5 min (d) 1. 25 104 min 126. The rate for a first order reaction is 0. 6932 10 ^2 moll ^1 min ^1 and the initial concentration of the reactants is 1 M , (^) T 1 / 2 is equal to [JIPMER (Med.) 2001] (a) 6. 932 min (b) 100 min (c) 0. 6932 10 ^3 min (d) 0. 6932 10 ^2 min 127. For a given reaction 1 / 2 1. Ka t . The order of the reaction is [KCET 2001] (a) 1 (b) 0 (c) 3 (d) 2 128. 75% of a first order reaction is completed in 30 minutes. What is the time required for 93.75% of the reaction (in minutes) [KCET 2001] (a) 45 (b) 120 (c) 90 (d) 60 129. A First order reaction is half completed in 45 minutes. How long does it need 99.9% of the reaction to be completed [AIIMS 2001] (a) 5 hours (b) 7.5 hours (c) 10 hours (d) 20 hours 130. A substance ‘ A’ decomposes by a first order reaction starting initially with [A] =2.00m and after 200 min [A] = 0.15m. For this reaction what is the value of k [AIIMS 2001] (a) 1.^29 ^10 ^2 min^1 (b)^2.^29 ^10 ^2 min^1 (c) 3. 29 10 ^2 min^1 (d) 4. 40 10 ^2 min^1 131. Which of the following statements about zero order reaction is not true [DCE 2001] (a) Its unit is sec ^1 (b) The graph between log (reactant) versus rate of reaction is a straight line (c) The rate of reaction increases with the decrease in concentration of reactants (d) Rate of reaction is independent of concentration of reactants 132. The given reaction (^2) NO O 2 2 NO 2 is an example of [CBSE PMT 2001; JIPMER 2002] (a) First order reaction (b) Second order reaction (c) Third order reaction (d) None of these 133. Order of a reaction is decided by [KCET 2002] (a) Pressure (b) Temperature (c) Molecularity
(d) Relative concentration of reactants
134. From the following which is a second order reaction [AMU 2002] (a) K 5. 47 10 ^4 sec^1 (b) K 3. 9 10 ^3 molelitsec^1 (c) K 3. 94 10 ^4 litmole-1sec^1 (d) K 3. 98 10 ^5 litmole-2sec^1 135. For the reaction A 2 B C , rate is given by R
[ A ][ B ]^2 then the order of the reaction is [AIEEE 2002] (a) 3 (b) 6 (c) 5 (d) 7
136. Units of rate constant of first and zero order reactions in terms of molarity M unit are respectively [AIEEE 2002] (a) sec ^1 , Msec ^1 (b) sec ^1 , M (c) Msec ^1 , sec ^1 (d) M , sec ^1 137. The reaction (^2) N 2 O 5 ⇌ (^2) N 2 O 4 O 2 is [MP PMT 2002]
(a) Bimolecular and second order (b) Unimolecular and first order (c) Bimolecular and first order (d) Bimolecular and zero order
138. The half-life period for a first order reaction is 693 seconds. The rate constants for this reaction would be [MP PET 2002] (a) 0.^1^ sec ^1 (b)^0.^01^ sec ^1 (c) 0. 001 sec ^1 (d) 0. 0001 sec ^1 139. For an elementary reaction, 2 A + B C + D the molecularity is [Kurukshetra CEE 2002] (a) Zero (b) One (c) Two (d) Three 140. If the order of the reaction x y hv xy is zero,
it means that the rate of [Kurukshetra CEE 2002] (a) Reaction is independent of temperature (b) Formation of activated complex is zero (c) Reaction is independent of the concentration of reacting species (d) Decomposition of activated complex is zero
141. For a first order reaction velocity constant, K 10 ^3 s ^1. Two third life for it would be [MP PET 2001; UPSEAT 2003] (a) 1100 s (b) 2200 s (c) 3300 s (d) 4400 s 142. In a reaction, the concentration of reactant is increased two times and three times then the increases in rate of reaction were four times and nine times respectively, order of reaction is [UPSEAT 2003] (a) Zero (b) 1 (c) 2 (d) 3 143. For a chemical reaction....can never be a fraction [EAMCET 2003] (a) Order (b) Half-life (c) Molecularity (d) Rate constant 144. 75% of a first order reaction was completed in 32 minutes when was 50% of the reaction completed
[AMU 1999; Kerala (Med.) 2003] (a) 16 min. (b) 24 min. (c) 8 min. (d) 4 min.
145. The decomposition of N 2 O 5 occurs as, 2 N 2 (^) O 5 4 NO 2 O 2 , and follows I st (^) order kinetics, hence [BVP 2003] (a) The reaction is unimolecular (b) The reaction is bimolecular (c) T 1 (^) / 2 a^0 (d) None of these 146. Which equation is correct for first order reactions [MP PMT 2003] (a) t 1 / 2 C^ ^1 (b) t (^) 1 / 2 C
(c) t 1 (^) / 2 C^0 (d) t 1 (^) / 2 C^1 /^2
147. For the reaction system 2 NO ( g ) O 2 ( g ) 2 NO 2 ( g ) volume is suddenly produced to half its value by increasing the pressure on it. If the reaction is of
first order with respect to O 2 and second order
with respect to NO , the rate of reaction will [AIEEE 2003] (a) Diminish to one fourth of its initial value (b) Diminish to one eighth of its initial value (c) Increase to eight times of its initial value (d) Increase to four times of its initial value
148. If the rate of the reaction is equal to the rate constant, the order of the reaction is [CBSE PMT 2003] (a) 3 (b) 0 (c) 1 (d) 2 149. The reaction A B follows first order kinetics. The time taken for 0.8 mole of A to produce 0. mole of B is 1 hour. What is the time taken for conversion of 0.9 mole of A to produce 0.675 mole of B [CBSE PMT 2003] (a) 2 hours (b) 1 hour (c) 0.5 hour (d) 0.25 hour 150. The unit of velocity constant in case of zero order reaction is [MP PMT 2004] (a) Concentration Time^1 (b)Concentrat ion-1^ Time- (c) Concentrat ion Time^2 (d)Concentrat ion-1^ Time 151. Which one of the following is wrongly matched [KCET 2004] (a) Saponification of CH 3 COOC 2 H 5 – Second order reaction (b) Hydrolysis of (^) CH 3 COOCH 3 – Pseudo uni- molecular reaction (c) Decomposition of H 2 O 2 – First order reaction (d) Combination of (^) H 2 and (^) Br 2 to give (^) HBr – Zero order reaction 152. Which of the following is an example of pseudo unimolecular reaction [Pb. CET 2001]
170. The rate of reaction between two reactants A and B decreases by a factor of 4 if the concentration of reactant B is doubled. The order of this reaction with respect to reactant B is [CBSE PMT 2005] (a) – 1 (b) – 2 (c) 1 (d) 2 171. If a substance with half life 3 days is taken at other place in 12 days. What amount of substance is left now [AFMC 2005] (a) 1/4 (b) 1/ (c) 1/16 (d) 1/ 172. The half-life of a first order reaction having rate constant K = 1.7 10 -^5 s -^1 is [BHU 2005] (a) 12.1 h (b) 9.7 h (c) 11.3 h (d) 1.8 h 173. For the reaction (^) A B C , it is found that doubling the concentration of A increases the rate by 4 times, and doubling the concentration of B doubles the reaction rate. What is the overal order of the reaction. [KCET 2005] (a) 4 (b) 3/ (c) 3 (d) 1 174. Which of the following reactions end in finite time [DPMT 2005] (a) 0 order (b) 1st order (c) 2nd order (d) 3rd order
Collision theory, Energy of activation
and Arrhenius equation
1. A large increase in the rate of a reaction for a rise in temperature is due to [EAMCET 1980; MP PET 1995] (a) The decrease in the number of collisions (b) The increase in the number of activated molecules
(c) The shortening of the mean free path (d) The lowering of the activation energy
2. Which of the following statements is not true according to collision theory of reaction rates (a) Collision of molecules is a precondition for any reaction to occur (b) All collisions result in the formation of the products
(c) Only activated collisions result in the formation of the products (d) Molecules which have acquired the energy of activation can collide effectively
3. 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
4. According to the collision theory of reaction rates, rate of reaction increases with temperature due to (a) Greater number of collisions (b) Greater velocity of the reacting molecules (c) Greater number of molecules have activation energy (d) None of the above 5. The reaction rate at a given temperature becomes slower, then [MP PMT 1993; DPMT 2000] (a) The free energy of activation is higher (b) The free energy of activation is lower (c) The entropy changes (d) The initial concentration of the reactants remains constant 6. A rise in temperature increases the velocity of a reaction. It is because it results in (a) An increased number of molecular collisions (b) An increased momentum of colliding molecules (c) An increase in the activation energy (d) A decrease in the activation energy 7. The number of collisions depend upon (a) Pressure (b) Concentration (c) Temperature (d) All the above 8. If Ef and Er are the activation energies of forward and reverse reactions and the reaction is known to be exothermic, then (a) E (^) f Er (b) E (^) f Er
(c) E (^) f Er (d) No relation can be given between Ef and Er as data are not sufficient
9. 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 collison (d) The energy gained by the molecules on colliding with another molecule 10. The energy of activation is (a) The energy associated with the activated molecules (b) Threshold energy – energy of normal molecules (c) Threshold energy + energy of normal molecules (d) Energy of products – energy of reactants 11. Which one of the following does not represent Arrhenius equation
(a) k Ae E / RT
(b) RT
E log e k log eA
(c) RT
E
k A
- 303 log 10 log 10
(d) k AE RT
12. On increasing the temperature, the rate of the reaction increases because of [MP PMT 1997] (a) Decrease in the number of collisions (b) Decrease in the energy of activation (c) Decrease in the number of activated molecules (d) Increase in the number of effective collisions 13. Energy of activation of a reactant is reduced by (a) Increased temperature (b)Reduced temperature (c) Reduced pressure (d) Increased pressure 14. The minimum energy a molecule should possess in order to enter into a fruitful collision is known as [Kurukshetra CEE 2002] (a) Reaction energy (b) Collision energy (c) Activation energy (d) Threshold energy 15. Activation energy is (a) The amount of energy to be added to the actual energy of a molecule so that the threshold energy is reached (b) The amount of energy the molecule must contain so that it reacts (c) The energy which a molecule should have in order to enter into an effective collision (d) The average kinetic energy of the molecule 16. The reason for almost doubling the rate of reaction on increasing the temperature of the reaction system by 10 oC is [J & K 2005] (a) The value of threshold energy increases (b) Collision frequency increases (c) The fraction of the molecule having energy equal to threshold energy or more increases (d) Activation energy decreases 17. The activation energy for a simple chemical reaction A B is Ea in forward direction. The activation energy for reverse reaction [CBSE PMT 2003] (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 18. Arrhenius equation is
(a) E RT dT
d^ ln^ K */ (b) ln^ E *^ / RT^2 dT
d K
(c) *^ /^2 ln E RT dT
d K (d) E RT dT
d K / ln (^) *
19. Activation energy of any reaction depends on (a) Temperature (b) Nature of reactants (c) Number of collisions per unit time (d) Concentration of reactants 20. Relation between rate constant and temperature by Arrhenius equation is
(a) RT
E log e A log eK a (b) RT
E log K A a
(c) log log 2 RT
K A Ea (^) e e (d)log A RT ln Ea ln K
21. 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 [Pb. CET 1985] (a) 20 kcal/mole (b) 15 kcal/mole (c) 10 kcal/mole (d) None of these 22. Which of the following plots is in accordance with the Arrhenius equation
(a) (b)
(c) (d)
23. The Arrhenius equation expressing the effect of temperature on the rate constant of a reaction is [MP PET 1997] (a) k e Ea / RT (b) k Ea / RT
(c) RT
E k log e a (d) k Ae Ea / RT
24. For a reaction, activation energy ( Ea ) 0 and rate constant ( K ) 3. 2 106 s ^1 at 300 K. What is the value of the rate constant at 310 K [KCE (a) 3.^2 ^10 ^12 s ^1 (b)^3.^2 ^10 6 s ^1 (c) 6. 4 1012 s ^1 (d) 6. 4 106 s ^1 25. Activation energy is given by the formula [DCE 1999]
(a)
(^) 12
2 1 1
2
- 303
log TT
T T R
E K
K (^) a
(b)
12
2 1 2
1
- 303 log TT
T T
R
E
K
K (^) a
(c)
12
1 2 2
1
- 303
log TT
T T
R
E
K
K (^) a
(d) None of these
26. A reaction having equal activation energies for forward and reverse reaction has [MP PMT 2002] (a) (^) H 0 (b) S 0 (c) Zero order (d) None of these 27. Collision theory is applicable to [MP PMT 2002] (a) First order reactions (b) Zero order reactions (c) Bimolecular reactions (d)Intra molecular reactions 28. A graph plotted between log K vs 1/ T for calculating activation energy is shown by [MP PET 2002]
(a) (b)
(c) (d)
1/T
log K 1/T
K
T
log K log T
log K
log K
1/ T
log K
1/ T
log K
1/ T
log K
1/ T
(b) dt
dHI dt
dHI dt
d H [ ] 2
[ 2 ] [ ] 1
(c) dt
dHI dt
dI dt
d H [ ] [ ] 2
[ ] 1
(d) dt
dHI dt
dI dt
2 d^ [ H^2 ] 2 [^2 ] [ ]
4. The rate law for a reaction between the substances A and B is given by, rate k [ A ] n^ [ B ] m. On doubling the concentration of A and halving the concentration of B , the ratio of the new rate to the earlier rate of the reaction will be as [AIEEE 2003] (a) ( ) 2
1 (^) m n (b)( m n )
(c) ( n m ) (d) 2 ( n^ m )
5. If we plot a graph between log K and T
1 by
Arrhenius equation, the slope is [UPSEAT 2001] (a) R
Ea (b) R
Ea
(c) R
Ea
- 303
(d) R
Ea
- 303
6. For an endothermic reaction, where H represents the enthalpy of the reaction in kJ / mol , the minimum value for the energy of activation will be [IIT 1992] (a) Less than H (b) Zero (c) More than H (d) Equal to H 7. The rate constant ( K )of one reaction is double of the rate constant ( K )of another reaction. Then the relationship between the corresponding activation energies of the two reactions ( E a and E a ) will be [MP PET 1994; UPSEAT 2001] (a) Ea ^ Ea (b) Ea ^ Ea (c) Ea ^ Ea (d) Ea ^ 4 Ea 8. The rate constant, the activation energy and the arrhenius parameter of a chemical reaction at 25 oC are 3. 0 10 ^4 s ^1 , 104. 4 kJ mol ^1 and 6. 0 10 14 s ^1 respectively. The value of the rate constant as (^) T is [IIT 1996] (a) 2. 0 1018 s ^1 (b) 6. 0 1014 s ^1 (c) Infinity (d)^3.^6 ^1030 s ^1 9. The H value of the reaction H (^) 2 Cl 2 ⇌ 2 HCl is 44. 12 kcal. If E 1 is the activation energy of the products, then for the above reaction [EAMCET 1997] (a) E 1 (^) E 2 (b) E 1 (^) E 2 (c) E 1 (^) E 2 (d) H is not related to E 1 and E 2 (e) None is correct 10. The temperature dependence of rate constant( k ) of a chemical reaction is written in terms of Arrhenius equation, K A. e E */ RT. Activation energy ( E *) of the reaction can be calculated by plotting [CBSE PMT 2003] (a) T k vs log
log (b) kvsT
(c) T
k vs log
1 (d) T
log k vs^1
11. Activation energy of a chemical reaction can be determined by [CBSE PMT 1998; AFMC 1999; BHU 2000] (a) Changing concentration of reactants (b) Evaluating rate constant at standard temperature (c) Evaluating rate constants at two different temperatures (d) Evaluating velocities of reaction at two different temperatures 12. The activation energy for a reaction is 9. 0 Kcal / mol. The increase in the rate constant when its temperature is increased from 298 K to 308 K is [JIPMER 2000] (a) 63% (b) 50% (c) 100% (d) 10% 13. Which of the following is the fastest reaction [Pb. CET 2002] (a) C O 2 ^250 C CO 2
1 (b) C O 2 ^500 C CO 2
1
(c) C O 2 ^750 C CO 2
1 (d) C O ^1000 C CO 2 2
1
14. The rate constant k, for the reaction N 2 O 5 ( g )
0 () 2
1 2 NO (^) 2 ( g ) 2 g is 2.^3 ^10 ^2 s ^1. Which equation given below describes the change of [ N 2 O 5 ]with time? [ N 2 O 5 ] 0 and [ N (^) 2 O 5 ] t correspond to concentration of N 2 O 5 initially and at time, t [AIIMS 2004] (a)[ N (^) 2 O 5 ] t [ N 2 O 5 ] 0 kt (b)[ N (^) 2 O 5 ] 0 [ N 2 O 5 ] t ekt (c) log 10 [ N (^) 2 O 5 ] t log 10 [ N 2 O 5 ] 0 kt
(d) kt O
O
t
[N ]
[N ]
In 2 5
2 50
15. For the reaction H CH (^) 3 COOCH 3 H 2 O CH (^) 3 COOH CH 3 OH The progress of the process of reaction is followed by (a) Finding the amount of methanol formed at different intervals (b) Finding the amount of acetic acid formed at different intervals (c) Using a voltmeter (d) Using a polarimeter 16. Half life of a reaction is found to be inversely proportional to the cube of its initial concentration. The order of reaction is [KCET 2002] (a) 2 (b) 5 (c) 3 (d) 4 17. The integrated rate equation is Rt log C 0 log Ct. The straight line graph is obtained by plotting [AIEEE 2002] (a) timev/slogCt (b) v/sCt time
1
(c) timev/sCt (d) Ct
v/s time
18. For which order reaction a straight line is obtained along with x – axis by plotting a graph between half life ( t 1 / 2 )and initial concentration ' a ' [RPE
(a) 1 (b) 2 (c) 3 (d) 0
19. The reaction, (^) X product follows first order kinetics. In 40 minutes the concentration of X changes from 0.1 M to 0.025 M Then the rate of reaction when concentration of X is 0.01 M (a) 1. 73 10 ^4 M min^1 (b) 3. 47 10 ^5 M min^1 (c) 3. 47 10 ^4 M min^1 (d) 1. 73 10 ^5 M min^1 20. A Substance undergoes first order decomposition. The decomposition follows two parallel first order reactions as
The percentage distribution of B and C are [Kerala PMT 2004] (a) 75% B and 25% C (b) 80% B and 20% C (c) 60% B and 40% C (d) 90% B and 10% C (e) 76.83% B and 23.17% C
Read the assertion and reason carefully to mark the correct option out of the options given below :
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not the correct explanation of the assertion. (c) If assertion is true but reason is false. (d) If the assertion and reason both are false. (e) If assertion is false but reason is true.
1. Assertion : Instantaneous rate of reaction is equal to dx / dt. Reason : It is the rate of reaction at any particular instant of time. 2. Assertion : Molecularity has no meaning for a complex reaction. Reason : The overall molecularity of a complex reaction is equal to the molecularity of the slowest step. 3. Assertion : If in a zero order reaction, the concentration of the reactant is doubled, the half-life period is also doubled. Reason : For a zero order reaction, the rate of reaction is independent of initial concentration. 4. Assertion : If the activation energy of a reaction is zero, temperature will have no effect on the rate constant. Reason : Lower the activation energy, faster is the reaction. 5. Assertion : According to steady state hypothesis, in a multistep reaction, the change in concentration with time for reactive intermediates is zero. Reason : The intermediates are so reactive that after a brief initial period their concentrations rise from zero to a small value and remains constant for most of the duration of the reaction. 6. Assertion : Half-life period of a reaction of first order is independent of initial concentration. Reason : Half-life period for a first order reaction 1 / 2 2.^303 log 2. K
t
7. Assertion : The photochemical reactions H (^) 2 Cl 2 2 HCl^ and H (^) 2 Br 2 2 HBr have equal quantum efficiencies. Reason : Both the reactions proceed by similar mechanism. 8. Assertion : Vision is not a photochemical reaction. Reason : Halogenation of alkenes is a photochemical reaction. 9. Assertion : Glow worm shows chemiluminescence. Reason : Glow worm emits light due to oxidation of protein, luciferin present in it. 10. Assertion : The rate of reaction is always negative. Reason : Minus sign used in expressing the rate shows that concentration of product is decreasing. 11. Assertion : The kinetic of the reaction mA nB pC m ' X n ' Y p ' Z obeys the rate expression as
kAm^ Bn dt
dx [][].
Reason : The rate of the reaction does not depend upon the concentration of C.
Rate of a reaction
A
B
C
k 1
k 2
k 1 = 1.26 10 –^4 s – (^1) k 1 = 3.8^ ^10 –^5 s –^1
480 Chemical Kinetics
Rate of a reaction
1 b 2 a 3 d 4 b 5 b
6 c 7 c 8 c 9 a 10 b
11 b 12 b 13 c 14 d 15 b
16 b 17 c 18 b 19 d 20 a
21 b 22 a 23 d 24 c 25 a
26 a 27 a 28 b 29 b 30 b
31 a 32 c 33 b 34 a 35 c
36 d 37 a 38 b 39 a 40 c
41 a 42 b
Rate law and Rate constant
1 d 2 c 3 a 4 b 5 a
6 a 7 a 8 c 9 b 10 b
11 b 12 d 13 a 14 c 15 d
16 d 17 c 18 a 19 c 20 c
21 b 22 a 23 a 24 d 25 b
26 a 27 a 28 c 29 c 30 d
31 d 32 c 33 c 34 d 35 b
36 c 37 c 38 a 39 c 40 b
41 a 42 d 43 a 44 c 45 c
46 a 47 b 48 b 49 c 50 b
51 b 52 a 53 a 54 d 55 d
56 c 57 d 58 b 59 b 60 b
61 c 62 d 63 c 64 b 65 c
66 d 67 b 68 c 69 c 70 b
71 d 72 d 73 b 74 b 75 d
76 b 77 b 78 c 79 c 80 c
81 b 82 b 83 c 84 a 85 a
86 c 87 c 88 a 89 c 90 c
91 b 92 b 93 c 94 b 95 b
96 d 97 b 98 c 99 a 100 c
101 b 102 d 103 c 104 c 105 a
106 d 107 a 108 b 109 c 110 b
111 c 112 d 113 b 114 b 115 d
116 d 117 b 118 d 119 a 120 b 121 d 122 b 123 d 124 c 125 d 126 b 127 d 128 d 129 b 130 a 131 ac 132 c 133 d 134 c 135 a 136 a 137 c 138 c 139 d 140 c 141 c 142 c 143 c 144 a 145 c 146 c 147 c 148 b 149 b 150 a 151 d 152 a 153 d 154 c 155 c 156 b 157 a 158 b 159 d 160 c 161 b 162 b 163 b 164 abd 165 ad 166 b 167 d 168 b 169 d 170 b 171 c 172 c 173 c 174 a
Collision theory, Energy of activation
and Arrhenius equation
1 b 2 b 3 b 4 c 5 a 6 d 7 d 8 b 9 c 10 b 11 d 12 d 13 a 14 d 15 a 16 b 17 d 18 b 19 b 20 a 21 c 22 a 23 d 24 b 25 a 26 ab 27 c 28 b 29 b 30 c 31 b 32 d 33 c 34 c 35 a 36 a
Photochemical reaction
1 a 2 a 3 c 4 b
Critical Thinking Questions
1 a 2 c 3 a 4 d 5 c 6 c 7 c 8 b 9 a 10 d 11 c 12 a 13 d 14 d 15 b 16 d 17 a 18 b 19 c 20 e
Assertion & Reason
1 b 2 b 3 b 4 b 5 a 6 a 7 d 8 e 9 a 10 d 11 a
Chemical Kinetics 481
Rate of a reaction
1. (b) Rate of reaction continuously decreases with time. 2. (a) The rate of reaction depends upon conc. of reactant, surface area of reactant, temperature, presence of light and catalyst. 3. (d) According to law of mass action. 4. (b) R K [ RCl ], if [ RCl ] =1/2, then rate = R /2. 5. (b) 2 2 4 , 32 9
6. (c) The rate of chemical reaction The product
of the molar conc. of the reactants (at constant T )
7. (c) Rate of reaction = 10
1 10
2 0. 1
dt
dx
0. 01 moldm ^3 min ^1
8. (c) As reaction progressing the concentration of the reactants decreases and the concentration of the product increases. 9. (a) dt
dNH dt
dH dt
d N ( ) 2
( ) 1 3
(^2 )^12 ^3 = 40 103
2
(^3)
60 10 ^3.
10. (b) Greater are the concentrations of the reactants, faster is the reaction. Conversely, as the concentrations of the reactants decreases, the rate of reaction also decreases. 11. (b) Ionic reactions are very fast reactions i.e. take place instantaneously. 12. (b) Rate = K ( A )^2 ( B )^1 on doubling the active mass of A the rate of reaction increase 4 times. 13. (c) ‘ A ’ will disappear at twice the rate at which ‘ B ’ will decrease. 14. (d) When volume is reduced to 4
1 , concentrations become four times.
16. (b) dt
dNH dt
dH dt
dN (^) 2 2 3 2
1 3
(^1)
- 001 0. 0015. 2
(^2) 3 kghr 1 dt
dH
18. (b) dt
dc refers as decrease in concentration of the reactant with time.
19. (d) The rate of a reaction depends upon concentration of reactant. 20. (a) dt
dD dt
dC dt
dB dt
d [ A ] [ ] [ ] ( ) 3
^1 .
21. (b) (^) N (^) 2 3 H 2 ⇌ 2 NH 3
t
NH t
H t
N
[ ] 2
[ ] 1 3
[ 2 ] (^123)
2 3 2 104 2
[ ] 3 2
[ ] (^3)
t
NH t
H
3 10 ^4 mollitre ^1 sec ^1
22. (a) Increase in concentration of B ^5 ^10 ^3 moll ^1 Time 10 sec
Rate of appearance ofB Timetaken
Increaseofconc.B
4 1 1 3 1 5 10 10 sec
5 ^10 moll moll Sec
24. (c) The rate of formation of (^) SO 3 is 1. 28 10 ^3 g / sec. 26. (a) ^10 ^10 2 t
t t
t r
r K
K ; For an increase of
temperature to 50 oC , i.e. 5 times, the rate increases by 25 times, i.e. 32 times.
28. (b) ^10 ^10 2 t
t t
t r
r K
K.
For an increase of temperature to 20 C i.e. 2 times, the rate increase by 22 times, i.e. 4 times.
29. (b) 2 10 10
t
t t
t r
r K
k
For an increase of temperature to 90 oCi.e. 9 times, the rate increases by 29 times i.e. 512.
30. (b) Catalyst increases the rate by decreasing the activation energy. 31. (a) For 10K rise in temperature, the rate of reaction nearly doubles. 32. (c) Temperature coefficient 2 298
308 25
35 o k
k C
C K
K K (^) o
K and
3 for most reactions.
33. (b) Catalyst decrease energy of activation. 34. (a) Thus both rate and rate constant K increase with temperature, r k ( reactant)n and k Ae Ea / RT 35. (c) Enzymes does not always increase activation energy.
