Answer:
Correct option is ₂⁴He
Step-by-step explanation:
Uranium-238 undergo alpha decay and produce Th-234 and alpha particle.
₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴ + energy
Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. It is also called helium nuclei. When atom undergoes the alpha emission the parent atom converted into the atom having mass number less than 4 and atomic number less than 2 as compared to parent atom.
Properties of alpha radiation:
Alpha radiations can travel in a short distance.
These radiations can not penetrate into the skin or clothes.
These radiations can be harmful for the human if these are inhaled.
These radiations can be stopped by a piece of paper.