Haloalkanes And Haloarenes

C–X bond length in P, Q and R follows the order Q > R > P.

C–X bond enthalpy in P, Q and R follows the order R > P > Q.

Relative reactivity toward S_N2 reaction in P, Q and R follows the order P > R > Q.

pK_a value of the conjugate acids of the leaving groups in P, Q and R follows the order R > Q > P.