For A + B → C + D, H = -20 kJ mol-1 , the activation energy of the forward reaction is 85 kJ mol-1. The activation energy for the backward reaction is…. kJ mol-1.

1. 105 2. 85
3. 40 4. 65

Subtopic:  Arrhenius Equation |
 77%
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Given that K is the rate constant for some order of any reaction at temperature T. Then the value of \(\lim\limits_{T \to \infty} log~k\) = (where A is the Arrhenius constant):
1. \(\frac{\text A}{2.303}\)
2. \(\text A\)
3. \(2.303~\text A\)
4. \(log~\text A\)
Subtopic:  Arrhenius Equation |
 50%
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For the elementary reaction M  N, the rate of disappearance of M increases by a factor of 8 upon doubling the concentration of M. The order of the reaction with respect to M will be:

1. 4

2. 3

3. 2

4. 1

Subtopic:  First Order Reaction Kinetics |
 76%
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The rate constant value for a zero-order reaction is 2 x10-2 mol L-1 sec-1. If the concentration of the reactant after 25 sec is 0.5 M, then the initial concentration of reactant is: 

1. 0.5 M

2. 1.25 M

3. 12.5M

4. 1.0 M

Subtopic:  Order, Molecularity and Mechanism |
 74%
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The rate constant for a second order reaction is 8x10-5 M-1 min-1 . How long will it take a 1M solution to be reduced to 0.5M?

1. 8.665 x 103 minute

2. 8 x 10-5 minute

3. 1.25 x 104 minute

4. 4x10-5 minute

Subtopic:  Order, Molecularity and Mechanism |
 69%
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The activation energy for a reaction is 9.0 kcal/mol. The increase in the rate constant when its temperature is increased from 298K to 308K is:

1. 10%

2. 100%

3. 50%

4. 63%

Subtopic:  Arrhenius Equation |
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For a certain reaction of order \('n'\) the time for half change \(t_{1/2}\) is given by; \(=,t_{1/2}=\dfrac{2-\sqrt2}{K}\times C^{1/2}_0,\) where \(K\) is rate constant and \(C_0\) is initial concentration. The value of \(n\) is:

1. 1

2. 2

3. 0

4. 0.5

Subtopic:  First Order Reaction Kinetics |
 65%
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In the following first order competing reactions:

A + Reagent  Product

B + Reagent  Product

The ratio of K1/K2 if only 50% of B will have been reacted when 94% of A has been reacted in same time is:

1. 4.06

2. 0.246

3. 2.06

4. 0.06

Subtopic:  First Order Reaction Kinetics |
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For a reversible reaction A k2k1 B, Ist order in both the directions, the rate of reaction is given by:

1. K1[A]

2. -K2B

3. K1[A] + K2[B]

4. K1[A] - K2[B]

Subtopic:  First Order Reaction Kinetics |
 55%
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The time for half-life of a first order reaction is 1 hr. What is the time taken for 87.5% completion of the reaction?

1. 1 hour

2. 2 hour

3. 3 hour

4. 4 hour

Subtopic:  First Order Reaction Kinetics |
 76%
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