$A$ and $B$ in the following reaction are :-

An organic compound $(A)$ with molecular formula $C_8H_8O$ forms an orange-red precipitate with $2,4-DNP$ reagent and gives a yellow precipitate on heating with iodine in the presence of sodium hydroxide. It neither reduces Tollens' or Fehlings' reagent,nor does it decolourise bromine water or Baeyer's reagent. On drastic oxidation with chromic acid,it gives a carboxylic acid $(B)$ having molecular formula $C_7H_6O_2$. Identify the compounds $(A)$ and $(B)$ and explain the reactions involved.

Match the examples given in Column $I$ with the name of the reaction in Column $II$ and identify the correct matches.

Column $I$ $(Example)$	Column $II$ $(Reaction)$
$a$. $CH_3COCl + H_2 \xrightarrow{Pd-C/BaSO_4} CH_3CHO$	Stephen's reaction
$b$. $C_6H_5CHO \xrightarrow{NaOH, \Delta} C_6H_5CH_2OH + C_6H_5COO^-Na^+$	Cannizzaro's reaction
$c$. $C_6H_6 + CH_3COCl \xrightarrow{AlCl_3} C_6H_5COCH_3$	Friedel-Crafts acylation
$d$. $R-CH_2-COOH \xrightarrow[H_2O]{Br_2/Red P} R-CH(Br)-COOH$	$HVZ$ reaction
$e$. $CH_3-CN \xrightarrow[\text{(ii) } H_2O/H^+]{\text{(i) } SnCl_2/HCl} CH_3CHO$	Stephen's reaction
$f$. $2 CH_3CHO \xrightarrow[\Delta]{NaOH} CH_3-CH=CHCHO$	Aldol condensation

The major products in the reaction $Br_3CCHO \stackrel{NaOH}{\longrightarrow}$ are $....$

The above conversion can be achieved by:

Which of the following reagents can form a hydrazone with alkanone?