No reaction occurs in which of the following equations?

Reduction potential of F2>Cl2>Br2>I2So F2 can displace Cl⊖,Br⊖, and I⊖ but not vice versa.Similarly, Cl2 can displace Br⊖ and I⊖but not vice versa and Br2 can displace only I⊝ but not vice versa.In (a), Fe (not Fe2+) is a better reducing agent than I⊝