For A + B $\to$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

For the elementary reaction M $\to$ 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

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

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

Which order of reaction obeys the relation t_1/2 = 1/Ka?

1. First

2. Second

3. Third

4. Zero

The chemical reaction, 2O₃ $\to$3O₂ proceeds as follows;

O₃ $\rightleftharpoons$O₂ + O .....(Fast)

O+O₃ $\to$ 2O₂ ....(Slow)

The rate law expression should be:

1. r = K[O₃]²

2. r = K[O₃]²[O₂]^-1

3. r = K[O₃][O₂]

4. unpredictable

The rate of reaction becomes 2 times for every 10°C rise in temperature. How the rate of reaction will increase when temperature is increased from 30°C to 80°C?

1. 16

2. 32

3. 64

4. 128

What fraction of a reactant showing first order remains after 40 minute if t_1/2 is 20 minute?

1. 1/4

2. 1/2

3. 1/8

4. 1/6

For the reaction 2NO₂ + F₂ → 2NO₂F, following

mechanism has been provided,

 NO₂ + F₂   $\stackrel{slow}{\to }$  NO₂F+F

NO₂ + F   $\stackrel{fast}{\to }$ NO₂F

Thus, rate expression of the above

reaction can be written as:

1. r = K[NO₂]²[F₂]

2. r = K[NO₂ ][F₂]

3. r = K[NO₂]

4. r = K[F₂]

For the reaction:

[Cu(NH₃)₄]²⁺ + H₂O_{$\rightleftharpoons$}[Cu(NH₃)₃H₂O]²⁺ + NH₃

the net rate of reaction at any time is given by, net rate =

2.0x10^-4 [Cu(NH₃)₄]²⁺[H₂O] - 3.0x10⁵ [Cu(NH₃ )₃ H₂0]²⁺[NH₃]

Then correct statement is/are :

1. rate constant for forward reaction = 2 x 10^-4

2. rate constant for backward reaction = 3 x 10⁵

3. equilibrium constant for the reaction = 6.6 x 10^-10

4. all of the above