question_answer

The half - life of a radioactive element A is the same as the mean-life of another radioactive element B. Initially both substances have the same number of atoms, then: [JEE ONLINE 22-04-2013]

A)             A and B both decay at the same rate always

B)             A and B will decay at the same rate initially

C)             A will decay at a faster rate B initially

D)             B will decay at faster rate A initially

Correct Answer: D

Solution :

[d]

or

Also rate of decay

Initially number of atoms (N) of both are equal but since  therefore B will decay at a faster rate than A