Answer: In alpha decay, an alpha particle is emitted.
Step-by-step explanation:
Alpha decay is defined as the decay process where an alpha particle is emitted. In this process, a heavier nuclei decays into a lighter nuclei. The alpha particle emitted carries a charge of +2 units and a mass of 4 units.
The emitted alpha particle is also known as helium nucleus.
In this decay process, the atomic number of the parent atom decreases by 2 units and the mass number decreases by 4 units.
The chemical equation for alpha decay process follows:
![_Z^A\textrm{X}\rightarrow _(Z-2)^(A-4)\textrm{Y}+_2^4\alpha](https://img.qammunity.org/2020/formulas/chemistry/high-school/em3ji94h9kmmxr13lorf6oy8np31oldr6n.png)
Hence, in alpha decay, an alpha particle is emitted.