question_answer

\[BC{{l}_{3}}\]does not exist as dimer but \[B{{H}_{3}}\]exist as dimer (\[{{B}_{2}}{{H}_{6}}\]) because

A) Chlorine is more electronegative than hydrogen

B)  There is \[p\pi \]-\[p\pi \]back bonding in \[BC{{l}_{3}}\] but \[B{{H}_{3}}\]does not contain such multiple bonding

C)  Large sized chlorine atoms do not fit in between the small boron atoms whereas small sized hydrogen atoms get fitted in between boron atoms

D)  None of the above