Answer
a) 0
b) 0
c) +1
d) +3
Work Step by Step
a) $Ne$ is an element and in standard state, all elements have an oxidation number of zero.
b) $Br_{2}$ is an element and in standard state, all elements have an oxidation number of zero.
c) $Cu^{+}$ is an ion and the oxidation number for ions corresponds to their charge which is +1 in this case
d) $Fe^{3+}$ is an ion and the oxidation number for ions corresponds to their charge which is +3 in this case