Consider the nuclear equation below.

superscript 239 subscript 94 upper p u right arrow variable x plus superscript 4 subscript 2 upper h e.

what is x?

X = ²³⁵₉₂U

Explanation:

The isotope of plutonium-239 undergo alpha decay and produced uranium-235.

Nuclear equation:

²³⁹₉₄Pu    →   ²³⁵₉₂U + ⁴₂He

Alpha decay:

Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4  and atomic number less than 2 as compared to parent atom the starting 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.

₉₂U²³⁸   →   ₉₀Th²³⁴  + ₂He⁴  + energy