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NEET Chemistry MCQ
Chemical Kinetics Mcq Neet Chemistry
Quiz 2
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Q.1
The rate constant k1 and k2 for two different reactions are 1016e-2000/T and 1015e-1000/T, respectively. The temperature at which k1 = k2 is ..[ CBSE 2008]
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a) 2000K
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b) 1000k
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c) (1000/2.303)k
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d) (2000/2.303)k
Explanation
1016e-2000/T and 1015e-1000/T Answer : (c)
Q.2
For which of the following reactions k310/k300 would be maximum?
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a) A + B → C; Ea = 50 kJ
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b) X + Y → Z; Ea = 40 kJ
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c) P + Q → R; Ea = 60 kJ
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d) E + F → G; Ea = 100 kJ
Explanation
From the formula From above equation, increase in rate constant is maximum for the reaction having maximum activation energy Answer : (d)
Q.3
For a reaction, the threshold energy is equal to
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a) activation energy + initial potential energy of reactants
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b) activation energy - initial potential energy of reactants
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c) activation energy
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d) initial potential energy of reactants
Explanation
Answer : (a)
Q.4
For which of the following reactions, the half-life is directly proportional to the initial concentration of the reactant? [ MPPMT 2006]
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a) zero order
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b) First order
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c) Second order
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d) Third order
Explanation
Answer : (a)
Q.5
Activation energy of a chemical reaction can be determined by ...[ CBSE 1997]
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a) evaluating rate constant at standard temperature
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b) evaluating velocities of reaction at two different temperature
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c) evaluating rate constants at two different temperatures
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d) changing concentration of reactants
Explanation
Answer : (c)
Q.6
Rate of gaseous reaction is given by the expression Rate = k[A][B] If the volume of reaction vessel is suddenly reduced to one fourth of initial volume, the reaction rate relating to original rate will be
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a) 1/10
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b) 1/8
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c) 8
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d) 16
Explanation
On decreasing the volume to one-fourth concentration or pressure of reactant gas increases 4 times Rate = k[4A][4B] Rate= 16k[A][B] New rate = 16× Old rate Answer : (d)
Q.7
The rate of reaction that does not involve gases, is not dependent on
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a) pressure
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b) catalyst
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c) concentration
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d) temperature
Explanation
Answer : (a)
Q.8
If the rate of the reaction is equal to the rate constant, the order of the reaction is ...[ CBSE 2003]
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a) 2
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b) 3
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c) 0
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d) 1
Explanation
IF order of reaction is zero then rate = rate constant Answer : (c)
Q.9
In general, with very 10°C rise in temperature, the rate of reaction becomes approximately ...
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a) ten times
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b) double
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c) half
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d) one tenth
Explanation
Answer : (b)
Q.10
Assertion The rate of reaction increases generally to 2 times for every 10°C rise temperature Reason Increase in temperature increases the collision frequency
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a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion
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b) The Assertion and Reason are true but Reason is not correct explanation of Assertion
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c) Assertion is true but, Reason is false
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d) Assertion is false but, Reason is true
Explanation
Increase in number of collision is not the only factor affecting increase in rate of reaction , but number of molecules having energy more than activation energy increases Answer : (b)
Q.11
A first order reaction is 50% completed in 30 minutes at 27°C. Its rate constant is ...[ BHU 1998]
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a) 2.31 ×10-2 min-1
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b) 3.21 ×10-5 min-1
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c) 4.75 ×10-2 min-1
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d) 1.33 ×10-3 min-1
Explanation
half time =30 min, use formula Answer : (a)
Q.12
For the reaction N2O5(g) → 2NO2(g) + ½O2(g) the value of rate of disappearance of N2O5 is given as 6.25×10-3 mol L-1s-The rate of formation of NO2 and O2 is given respectively as ...[ CBSE 2010]
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a) 6.25×10-3 mol L-1 s-1 and 6.25 ×10-3 mol L-1 s-1
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b) 1.25×10-2mol L-1 s-1 and 3.125×10-3mol L-1 s-1
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c) 6.25×10-3 mol L-1 s-1 and 3.125 ×10-3 mol L-1 s-1
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d) 1.25×10-2 mol L-1 s-1 and 6.25 ×10-3 mol L-1 s-1
Explanation
Answer : (b)
Q.13
In a chemical reaction two reactants take part. The rate of reaction is directly proportional to the concentration of one of them and inversely proportional to the concentration of the other. the order of reaction is ...[ CPMT 2003]
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a) zero
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b) 1
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c) 2
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d) 4
Explanation
Since rate = k[A]1[B]-1 order of reaction = 1 +(-1) = 0 Answer : (a)
Q.14
Assertion The molecularity of the reaction, H2+Br2 → 2HBr is 2 Reason The order of this reaction is 3/2
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a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion
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b) The Assertion and Reason are true but Reason is not correct explanation of Assertion
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c) Assertion is true but, Reason is false
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d) Assertion is false but, Reason is true
Explanation
Answer : (b)
Q.15
If the rate of reaction between A and B is given by rate = k[A][B]2, then the reaction is
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a) First order in A
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b) Second order in B
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c) Third order overall
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d) All are correct
Explanation
Answer : (d)
Q.16
The rate constant of first order reaction is 10-2 min-the half-life period of reaction is .... [AFMC 2001]
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a) 693 min
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b) 69.3 min
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c) 6.93 min
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d) 0.693 min
Explanation
Answer : (b)
Q.17
The half-life of a first order reaction having rate constant k=2.1×10-5 sec-1 is ...[ JIPMER 2006]
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a) 3.27 hr
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b) 6 hr
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c) 8.12hr
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d) 9.17hr
Explanation
For first order reaction half time Answer : (d)
Q.18
Half-life of reaction is halved as the initial concentration of the reactant is doubled. The order of reaction is
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a) 0.5
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b) 1.0
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c) 2.0
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d) 0
Explanation
Answer : (c)
Q.19
Catalyst increases rate of reaction by ...[ CPMT 1994]
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a) decreasing equilibrium constant
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b) decreasing threshold energy
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c) decreasing activation energy
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d) none of the above
Explanation
Answer : (c)
Q.20
For a chemical reaction, A → E, it is found that rate of reaction is doubled when the concentration of A is increased four times. The order of the reaction is
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a) zero
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b) 1/2
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c) 1
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d) 2
Explanation
Rate ∝ [A]n Now concentration is increased four times and rate becomes doubled ∴ n = 1/2 Answer : (b)
Q.21
DDT on exposure to water decomposes (t1/2 = 10 years). How much time it will take for decomposition to 99% according to first order kinetics?
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a) 50 yrs
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b) 70 yrs
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c) 500 yrs
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d) 700 yrs
Explanation
Use following formula, first order reaction Therefore from above two formula Answer : (b)
Q.22
Which of the following statements for the order of reaction is incorrect? [ CBSE 2011]
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a) Order of reaction is always whole number
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b) Order can be determined only only experimentally
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c) Order is not influenced by stoichiometric coefficient of the reactants
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d) Order of reaction is sum of power to the concentration terms of reactants to express the rate of reaction
Explanation
Answer : (a)
Q.23
A zero order reaction is one
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a) in which reactants do not react
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b) in which one of the reactants is in large excess
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c) whose rate is uniform and not affected by time
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d) whose rate increases with time
Explanation
Answer : (c)
Q.24
Positive catalyst lower the activation energy of the reaction where as heat of reaction remains same Reason Heat of reaction is equal to the difference between activation energies for forward and the backward reactions
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a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion
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b) The Assertion and Reason are true but Reason is not correct explanation of Assertion
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c) Assertion is true but, Reason is false
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d) Assertion is false but, Reason is true
Explanation
Answer : (b)
Q.25
The rate at which a substance reacts depends upon its
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a) atomic mass
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b) equivalent mass
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c) molecular mass
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d) active mass
Explanation
Answer : (d)
Q.26
The reaction A → B follows first order kinetics. The time taken for 0.8 mol of A to produce 0.6mol 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 ..[ CBSE 2003]
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a) 0.25 hour
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b) 2 hours
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c) 1 hour
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d) 0.5 hour
Explanation
use formula to calculate first for k R0.8 and R= 0.6 value of k is 0.288 hr-1 use again above formula for t, R0.9 and R = 0.675 t = 1 hr Answer : (c)
Q.27
Number of molecules of a substance present in 1 litre volume is known as [ MPPMT 1993]
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a) molar concentration
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b) active mass
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c) activity
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d) none of the above
Explanation
Answer : (b)
Q.28
The half-life of a substance in a first order reaction is 15 minutes. the rate constant is ...[ AIIMS 2002]
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a) 2.46 ×102 min-1
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b) 4.62 ×10-2 min-1
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c) 3 ×10-5 min-1
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d) 3×10-9 min-1
Explanation
Use half-life formula for first order reaction Answer : (b)
Q.29
Number of molecules must overcome an energy barrier is given by
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a) A
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b) k
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c) e-Ea/RT
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d) Ea
Explanation
e-Ea/RT this expression counts the fraction of the molecules present in a gas which have energies equal to or in excess of activation energy at a particular temperature Answer : (c)
Q.30
Identify the order of reaction whose rate constant is k=3.2×10-5L mol-1 s-1
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a) 0
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b) 1
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c) 2
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d) 3
Explanation
from the general formula for unit of k comparing the power of rate constant n-1=1 n=2 ∴ Second order reaction Answer : (c)
0 h : 0 m : 1 s
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