Above question is incomplete. Complete question is
What is the missing number in the nuclear reaction 175 78 pt -- 4 2 He plus 76 Os?
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Solution:
Reaction involved in present nuclear event is
175 78 Pt → 4 2 He + 76 Os
In above nuclear reaction, atomic mass number of Os is missing. The atomic mass number of Os = 175 - 4 = 171
Thus, complete nuclear can be written as
175 78 Pt → 4 2 He + 171 76 Os
