For the reaction sequence given below, the correct statement(s)...

For the reaction sequence given below, the correct statement(s) is(are)

(In the options,

X

is any atom other than carbon and hydrogen, and it is different in

\mathbf{P}, \mathbf{Q}

and

\mathbf{R}

)

Options

AC-X bond length in $\mathbf{P}, \mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{Q}>\mathbf{R}>\mathbf{P}$ .
BC-X bond enthalpy in $\mathbf{P}, \mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{R}>\mathbf{P}>\mathbf{Q}$ .
CRelative reactivity toward $\mathrm{S}_{\mathrm{N}} 2$ reaction in $\mathbf{P}, \mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{P}>\mathbf{R}>\mathbf{Q}$ .
D $\mathrm{p} K_{\mathrm{a}}$ value of the conjugate acids of the leaving groups in $\mathbf{P}, \mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{R}>\mathbf{Q}>\mathbf{P}$ .

B. C-X bond enthalpy in $\mathbf{P}, \mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{R}>\mathbf{P}>\mathbf{Q}$ .

(A) Wrong: bond length order

\mathrm{Q}>\mathrm{P}>\mathrm{R}

(B) Correct: Bond enthalpy

\mathrm{R}>\mathrm{P}>\mathrm{Q}

\mathrm{S}_{\mathrm{N}} 2

reactivity

\quad \mathrm{Q}>\mathrm{P}>\mathrm{R}

(D) Wrong:

\mathrm{pKa}(\mathrm{HI} <\mathrm{HBr} <\mathrm{HF}) \quad \mathrm{R}>

>\mathrm{Q}(\mathrm{pKa})