Chemical Kinetics Multiple Choice Questions and Answers

Questions
1 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
A 20 minutes
B 30 minutes
C 35 minutes
D 75 minutes

Answer: 30 minutes
2 The half life period of a radioactive element is 140 days. After 560 days , 1 g of element will be reduced to
A (1/2)g
B (1/4)g
C (1/8)g
D (1/16)g

Answer: (1/16)g
3 The correct difference between first and second order reactions is that
A A first order reaction can be catalysed; a second order reaction cannot be catalysed.
B The half life of a first order reaction does not depend on [A0]; the half life of a second order reaction does depend on [A0].
C The rate of a first order reaction does not depend on reactant concentrations; the rate of a second order reaction does depend on reactant concentrations.
D The rate of a first order reaction does depend on reactant concentrations; the rate of a second order reaction does not depend on reactant concentrations.

Answer:The half life of a first order reaction does not depend on [A0]; the half life of a second order reaction does depend on [A0].
4 After 2 hours, a radioactive substance becomes (1/16)th of original amount. Then the half life ( in min) is
A 60 minutes
B 120 minutes
C 30 minutes
D 15 minutes

Answer: 30 minutes
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