# Radioactivity – 3

3. The half life time of a radio active elements of x is the same as the mean life of another radioactive element Y. Initially they have same number of atoms, then :

(a) y will decay faster thean x
(b) x will decay faster then y
(c) x and y will decay at the same rate at all time
(d) x and y will decay at the same rate initially

Explanation
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