Question

The half life period of a radioactive element X is same as the mean lifetime of another radioactive element Y. Initially they have the same number of atoms. Then,

• A. X will decay faster than Y
• B. Y will decay faster than X
• C. X and Y have same decay rate initially
• D. X and Y decay at same rate always

Answer 1

Answer: (A)

X will decay faster than Y

Given: $\frac{ln2}{{\lambda }_X}=\frac{1}{{\lambda }_Y}$
Hence, ${\lambda }_X=ln2\times {\lambda }_Y$
Higher the rate constant value, higher the activity.
Hence, X decays faster than Y.