Haloalkanes and Haloarenes

For the reaction sequence given below, the correct statement(s) is(are) [figure] (In the options, X is any atom other than carbon and hydrogen, and it is different in P, Q and R)

1. C−X bond length in P, Q and R follows the order Q > R > P.
2. C−X bond enthalpy in P, Q and R follows the order R > P > Q.
3. Relative reactivity toward SN2 reaction in P, Q and R follows the order P > R > Q.
4. pKa value of the conjugate acids of the leaving groups in P, Q and R follows the order R > Q > P.