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) r = K[A]2[B]

(b) r=K[A][B]

(c) r= K[A]2

(d) r= K[A][C]

Subtopic:  Definition, Rate Constant, Rate Law |
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For the reaction N2 + 3H2  2NH3, the rate d[NH3]dt = 2x10-4 Ms-1 .Therefore, the rate -d[N2]dt is given as:

(1) 10-4 Ms-1

(2) 104 Ms-1

(3) 10-2 sM-1

(4) 10-4 sM-1

Subtopic:  Definition, Rate Constant, Rate Law |
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If 'a' is the initial concentration of a substance which reacts according to zero order kinetics and K is rate constant, the time for the reaction to go to completion is:

(a) a/K

(b) 2/Ka

(c) K/a

(d) 2K/a

Subtopic:  First Order Reaction Kinetics |
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In a reaction, the rate expression is, rate = K[A][B]2/3[C]0 , the order of reaction is:

1. 1

2. 2

3. 5/3

4. zero

Subtopic:  Order, Molecularity and Mechanism |
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The rate of a reaction get doubles when the temperature changes from 7°C to 17°C. By what factor will it change for the temperature change from 17°C to 27°C?

(a) 1.81

(b) 1.71

(c) 1.91

(d) 1.76

Subtopic:  Arrhenius Equation |
 71%
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For the elementary step,

(CH3)3.CBr(aq) → (CH3)3C+ (aq) + Br- (aq) the molecularity is:

(a) zero

(b) 1

(c) 2

(d) cannot ascertained

Subtopic:  Order, Molecularity and Mechanism |
 77%
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When ethyl acetate was hydrolysed in pressure 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 6.25 X10-5sec-1. Thus, it may be concluded that:

(1) H2SO4 is stronger than HCI

(2) H2SO4 is weaker than HCl

(3) H2SO4 and HCl both have the same strength

(4) the data are not sufficient to compare the strength of H2SO4 and HCI

Subtopic:  Definition, Rate Constant, Rate Law | Catalyst |
 77%
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The half time of a second order reaction is:

(1) inversely proportional to the square of the initial concentration of the reactants

(2) inversely proportional to the initial concentration of the reactants

(3) proportional to the initial concentration of reactants

(4) independent of the initial concentration of reactants

Subtopic:  First Order Reaction Kinetics |
 77%
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The half-life period of a first order chemical reaction is 6.93 minutes. The time required for the completion of 99% of the chemical reaction will be (log 2 = 0.301):

(a) 23.03 minutes

(b) 46.06 minutes

(c) 460.6 minutes

(d) 230.3 minutes

Subtopic:  First Order Reaction Kinetics |
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A zero order reaction is one:

(1) In which reactants do not react

(2) In which one of the reactants is in large excess

(3) Whose rate does not change with time

(4) Whose rate increases with time

Subtopic:  Order, Molecularity and Mechanism |
 73%
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