Two radioactive isotopes,X and Y,both decay to stable products.The half-life of X is about a day,while that of Y is about a week.Suppose a radioactive sample consists of a mixture of these two nuclides.If the mixture is such that the activities arising from X and Y are initially equal,then a few days later the activity of the sample will be due
A)predominantly to Y.
B)predominantly to X.
C)entirely to Y.
D)to X and Y equally.

Question

Quizplus · Accepted Answer

Since the half-life of Y is much longer than that of X, Y will decay much more slowly than X. Therefore, after a few days, most of the X will have decayed, while a significant amount of Y will remain. As a result, the activity of the sample will be predominantly due to Y.

Two Radioactive Isotopes,X and Y,both Decay to Stable Products