Answer: The missing part in the nuclear reaction is Pb.
Explanation:
The given nuclear reaction is a type of alpha decay process. In this process, the nucleus decays by releasing an alpha particle. The mass number of the nucleus is reduced by 4 units and atomic number is also decreased by 2 units. The particle released is a helium nucleus.
The general equation representing alpha decay process is:
[tex]_{Z}^{A}\textrm{X}\rightarrow _{Z-2}^{A-4}\textrm{Y}+_2^4\alpha[/tex]
For the given equation of a nuclear reaction:
[tex]^{212}_{84}\textrm{Po}\rightarrow ^{208}_{82}?+^4_2\textrm{He}[/tex]
The nucleus having atomic number of 82 is Lead and the symbol used to represent this element is 'Pb'
Thus, the missing part in the nuclear reaction is Pb.
