Which reaction is not feasible?
2KI + Br22KBr + I2
2KBr + I2 2KI + Br2
2KBr + Cl2 2KCl + Br2
2H2O + 2F2 4HF + O2
Oxidising ability decreases from F2 to I2. A more active non metal displaces less active non metal from its solution.