The variation of decay rate of two radioactive samples A and B with time is shown in fig.

Which of the following statements are true?

Options

A. Decay constant of A is greater than that of B, hence A always decays faster than B
B. Decay constant of B is greater than that of A, but its decay rate is always smaller than that of A
C. Decay constant of A is greater than that of B, but it does not always decay faster than B
D. Decay constant of B is smaller than that of A but still its decay rate becomes equal to that of A at a later instant

Answer

C, D

Explanation

form fig. we find that rate of decay of A is faster than that of B. It means decay constant of A is greater than that of B.
However, the two curves intersect at P. Beyond P, B decays faster than A. And at P, decay rate of both A and B is the same. Hence, choice (c) and (d) are correct.