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?

Identify the product ' B ' in following reaction.

Ethanal $\xrightarrow{\text { dil } \mathrm{NaOH}} A \xrightarrow[\mathrm{H}_2 \mathrm{O}]{\Delta} B$