Answer is: mass number of element is 234. <span>Alpha particle is nucleus of a </span>helium-4<span> atom, which is made of two </span>protons<span> and two </span>neutrons<span>. </span>²³⁸U → ²³⁴Th + α (alpha particle). Alpha decay is radioactive decay<span> in which an </span>atomic nucleus<span> emits an </span>alpha particle<span> (helium nucleus) and transforms into an atom with </span>an atomic number that is reduced by two <span>and </span>mass number<span> that is reduced by four</span><span>.</span>
The sum of the masses of potassium and iodine equals the mass of the product, potassium iodide. The results are consistent with he law of conservation of mass.
