The correct order of reactivity for reaction involving cleavage of C-X bond in following compounds is

Which from following is a strong field ligand?

Calculate vapour pressure of pure volatile liquid $B$ at given temperature if mole faction of liquid $B$ and vapour pressure of pure volatile liquid $A$ are 0.4 and 400 mm Hg respectively.

$$ \left[\mathrm{P}_{\text {total }}=600 \mathrm{~mm} \mathrm{Hg}\right] $$

Identify the monomer used in preparation of polyacrylonitrile?