The expression for a neutron starting a fission reaction is incorrectly written as \( ^{01}n + ^{235}{92}U \). The correct notation for a neutron is \( ^{1}{0}n \) (or simply \( n \)), which indicates a mass number of 1 and an atomic number of 0.
Therefore, the correct response is:
A neutron should be expressed as \( ^{1}{0}n \), not \( ^{0}{1}n \).