$ \begin{array}{1 1}(a)\;\text{Benzenediazonium salt react with water to yield benzene}\\(b)\;\text{Fluro benzene can be obtained from benzenediazonium salt by adding the reagent KF followed by heating}\\(c)\;PhN_2^{\oplus}\text{ couples with }PhNMe_2\text{ and not with }PhCH_3\\(d)\;Me-C_6H_5\text{ is active to couple with }P-N_2^{\oplus}-C_6H_4-NMe_2\end{array}$
