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\(_{86}^{226}\textrm{Ra}\rightarrow_{84}^{222}+_{2}^{4}\textrm{He}\)

\(_{84}^{210}\textrm{Po}\rightarrow_{82}^{206}\textrm{Pb}+_{Z}^{A}\textrm{X}\)

X has mass number 4 and atomic number 2 and so is an alpha particle \(_{2}^{4}\textrm{He}\)

\(_{84}^{210}\textrm{Po}\rightarrow_{82}^{206}\textrm{Pb}+_{2}^{4}\textrm{He}\)