Which of the following reaction is not feasible ?

Question

$\begin{array}{1 1} 2 K_1 +Br_2 \to 2kBr +I_2 \\ 2KBr + I_2 \to 2KI +Br_2 \\ 2KBr +cl_2 \to 2Kcl +Br_2 \\ 2H_2O +F_2 \to 4HF +O_2 \end{array}$