Question

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

Which of the following statements are true?

1. Decay constant of A is greater than that of B, hence A always decays faster than B.
2. Decay constant of B is greater than that of A but its decay rate is always smaller than that of A.
3. Decay constant of A is greater than that of B but it does not always decay faster than B.
4. 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.

Options

• a and b

• a and c

• b and d

• c and d

Answer 1

c and d

Explanation:

It can be observed from the figure that the slope of curve A is greater than that of curve B, it means the rate of decay is faster for A than that of B.

According to Rutherford and Soddy's law for radioactive decay `-((dN)/(dt)) ∝ λ`, where decay. Hence at point P, the rate of decay for both A and B is the same.