Explanation

(b)
In ${XeF}_{5}^{+},$ Xe atom has only seven electrons , $i.e$., $5s^{2}\ 5p^{5}$. Here two 5p electrons are promoted to 5d-sublevel. Then 5s, three 5p and two 5d orbitals hybridize to give six $sp^{3}d^{2}$ hybrid orbitals in an octahedral geometry. Out of these five orbitals are singly occupied which form sigma bonds with five F atoms. The sixth hybrid orbital is occupied by a lone pair in $trans$ position giving a square pyramid structure.