Match the species in Column I with the bond order in Column II.

Thus, on calculating we can get the bond order:
(i)
(c);
So, Bond Order of NO =
(15-10)
= 2.5
(ii)
(d);
So, Bond Order of CO =
(14-8)
= 3.
(iii)
(a);
So, Bond Order of O2- =
(10-7)
= 1.5
(iv)
(b);
So, Bond Order of O2 =
(16-12)
= 2.