Unit VII: Chemical Kinetics - Online Test

Q1. In a homogeneous reaction A →B + C + D , the initial pressure was P0 and after time t it was P. expression for rate constant in terms of P0, P and t will be
Answer : Option A
Explaination / Solution:




Q2. If 75% of a first order reaction was completed in 60 minutes , 50% of the same reaction under the same conditions would be completed in
Answer : Option B
Explaination / Solution:

t75% = 2t50%

t50% = (t75% / 2) = (60/2) = 30 min


Q3. The half life period of a radioactive element is 140 days. After 560 days , 1 g of element will be reduced to
Answer : Option D
Explaination / Solution:

In 140 days initial concentration reduced to (1/2)g

In 280 days initial concentration reduced to (1/4)g

In  420 days initial concentration reduced to (1/8)g

In 560 days initial concentration reduced to (1/16)g


Q4. The correct difference between first and second order reactions is that
Answer : Option B
Explaination / Solution:

For a first order reaction

t1/2 = 0.6932/k

For a second order reaction




Q5. After 2 hours, a radioactive substance becomes (1/16)th of original amount. Then the half life ( in min) is
Answer : Option C
Explaination / Solution:


4t1/2 = 2 hours

t1/2 = 30 min