# NEET Physics Nuclei Questions Solved

The half life period of a radioactive element X is same as the mean life time of another radioactive element Y. Initially both of them have the same number of atoms. Then

(a) X and Y have the same decay rate initially
(b) X and Y decay at the same rate always
(c) Y will decay at a faster rate than X
(d) X will decay at a faster rate than Y

(c) ${\left({\mathrm{T}}_{1/2}\right)}_{\mathrm{x}}={\left({\mathrm{t}}_{\mathrm{mean}}\right)}_{\mathrm{y}}$

Also rate of decay = $\mathrm{\lambda }$N
Initially number of atoms (N) of both are equal but since ${\mathrm{\lambda }}_{\mathrm{y}}>{\mathrm{\lambda }}_{\mathrm{x}}$ therefore, y will decay at a faster rate than x.

Difficulty Level:

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