Identify the unknown (mathrm{X}) in the following decays: a. ({ }_{86}^{222} mathrm{Rn} ightarrow{ }_{84}^{218} mathrm{Po}+mathrm{X}) b. ({ }_{88}^{228} mathrm{Ra} ightarrow{ }_{89}^{228} mathrm{Ac}+mathrm{X}) c.

Identify the unknown \(\mathrm{X}\) in the following decays:

a. \({ }_{86}^{222} \mathrm{Rn} \rightarrow{ }_{84}^{218} \mathrm{Po}+\mathrm{X}\)

b. \({ }_{88}^{228} \mathrm{Ra} \rightarrow{ }_{89}^{228} \mathrm{Ac}+\mathrm{X}\)

c. \({ }_{54}^{140} \mathrm{Xe} \rightarrow{ }_{55}^{140} \mathrm{Cs}+\mathrm{X}\)

d. \({ }_{29}^{64} \mathrm{Cu} \rightarrow{ }_{28}^{64} \mathrm{Ni}+\mathrm{X}\)