$PCl_5$ reacts with propanone to give:

Identify the structure of $B$ in the following reaction sequence:
$2,6-\text{dimethylcyclohexane-1,4-dione} + \text{ethane-1,2-diol}$ $\xrightarrow{H^+} A$ $\xrightarrow[2. H_3O^+]{1. LiAlH_4} B$

Which is the most suitable reagent for the following conversion?
$CH_3-CH=CH-CH_2-CO-CH_3 \rightarrow CH_3-CH=CH-CH_2-COO^- + CHI_3$

Which of the following aldehydes gives a red precipitate with Fehling solution?

Which one of the following will be most readily dehydrated in acidic condition?

Which product is not formed in the following reaction $:-$ $CH_3CHO + CH_3-CH_2-CHO \xrightarrow[\text {(ii) } \Delta]{\text {(i) } NaOH}$