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

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

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 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