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Question
A radioactive nucleus ‘A’ undergoes a series of decays according to the following scheme:
The mass number and atomic number of A are 180 and 72 respectively. What are these numbers for A4?
Solution
A has mass number as 180 and atomic number 172.
Formation of A1 by α-decay:
Formation of A2 by β decay:
Formation of A4:
In r-decay, mass number and atomic number remain the same.
Thus,
Mass number of A4 = 172
Atomic number of A4 = 169
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