In gaseous reactions important for the understanding of the upper atmosphere H₂O and O react bimolecularly to form two OH radicals. $∆$H for this reaction is 72kJ at 500 K and E_a is 77 kJ mol^-1, then E_a for the bimolecular recombination of two OH radicals to form H₂O and O is:

1. 3 kJ mol^-1

2. 4 kJ mol^-1

3. 5 kJ mol^-1

4. 7 kJ mol^-1

For an exothermic chemical process occurring in two steps as;

(i) A+B$\to$X(Slow)

(ii) X$\to$AB (Fast)

The progress of the reaction can be best described by:

1.		2.
3.		4.	All of the above.

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?

1. 1.81

2. 1.71

3. 1.91

4. 1.76

In the Arrhenius equation K = Ae^-E_a/RT, the quantity e^-E_a/kT is referred as:

1. Boltzmann factor.

2. Frequency factor.

3. Activation factor.

4. None of the above.

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.

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%

For a given reaction, the presence of a catalyst reduces the energy of activation by 2 kcal at 27 ^oC. The rate of reaction will be increased by:

1. 20 times

2. 14 times

3. 28 times

4. 2 times

Rate constant of reaction can be expressed by Arrhenius equation as,

                             $K=A{e}^{\raisebox{1ex}{$-E_a$}\!\left/ \!\raisebox{-1ex}{$RT$}\right.}$   

In this equation, ${\mathrm{E}}_{\mathrm{a}}$ represents:

1. the energy above which all the colliding molecules will react

2. the energy below which colliding molecules will not react

3. the total energy of the reacting molecules at a temperature, T

4. the fraction of molecules with energy greater than the activation energy of the reaction

The activation energies of the forward and backward reactions in the case of a chemical reaction are 30.5 and 45.4 KJ/mol respectively. The reaction is

1. Exothermic

2. Endothermic

3. Neither exothermic nor endothermic

4. Independent of temperature