Answer
See explanation
Work Step by Step
A compound nucleus occurs when a projectile and a target nucleus are within the range of nuclear forces in specific $time$.
It requires about $10^{–15} s$ to fully distribute energy in large nucleus, hence create a compound nucleus.
The target nucleus should stay at least for $10^{–22} s$ to become a compound nucleus or else it does not have the criteria to become a compound nucleus.
