The rate of a reaction decreased by 3.555 times when the temperature was changed from 40^oC to 30^oC. The activation energy (in kJ mol^–1) of the reaction is _______.

Take; R = 8.314 J mol^–1 K^–1 ln 3.555 = 1.268

The number of molecules with energy greater than the threshold energy for a reaction increases five fold by a rise of temperature from 27^oC to 42^oC. Its energy of activation in J/mol is _____.
(Take ln 5 = 1.6094; R = 8.314 J mol^–1 K^–1)

If 75% of a first order reaction was completed in 90 minutes, 60% of the same reaction would be completed in approximately (in minutes) _______.

(Take : log 2 = 0.30; log 2.5 = 0.40)

A sample of milk splits after 60 min. at 300 K and after 40 min. at 400 K when the population of lactobacillus acidophilus in it doubles. The activa tion energy (in kJ/ mol) for this process is closest to__________.

(Given, R = 8.3 J mol^–1 K^–1, $$\ln \left( {{3 \over 2}} \right) = 0.4$$, e^–3 = 4.0)