Identify the product ' B ' in the following sequence of reactions.

Methyl magnesium bromide $\xrightarrow{\mathrm{CdCl}_2} \mathrm{~A}\xrightarrow{\mathrm{CH}_3 \mathrm{COCl}} \mathrm{~B}$

Identify the compound formed by action of chromyl chloride on toluene in presence of $\mathrm{CS}_2$ and hydrolysed further?

Identify the reagent $R$ used in following reaction.

Ketone $$\buildrel R \over \longrightarrow$$ semi carbazone

Identify the product of following reaction.

Formaldehyde + Benzaldehyde $$ \xrightarrow[\mathrm{H}_3 \mathrm{O}^{+}]{\text {conc. } \mathrm{NOH}} \text { product }$$