Explain radioactivity and identify the decay product of Radon-222 nuclide if it undergoes alpha decay.

a) Radioactivity is the spontaneous emission of radiation (such as alpha particles, beta particles, or gamma rays) from the unstable nuclei of certain atoms.

b) The question states "Radon nuclide ($^{222}_{86}\text{Ra}$)" decays. Given that Radon has an atomic number of 86 (symbol Rn), and Radium (Ra) has an atomic number of 88, we will assume the element is Radon ($^{222}_{86}\text{Rn}$) as indicated by the name "Radon nuclide" and the atomic number 86.

An alpha particle is represented as $^{4}_{2}\text{He}$.
The decay equation for alpha emission is:

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