What is the characteristic odor of nitrobenzene?

Consider the following reaction sequence:
$B \xleftarrow{NaBH_4} CH_2=CH-CHO \xrightarrow{H_2/Pt} A$
Identify $A$ and $B$.

Which of the following reagents is used for the following conversion?
$CH_3-CH=CH-CHO \longrightarrow CH_3-CH=CH-CH_2OH$

What is the main product obtained by the cross-aldol condensation of benzene carbaldehyde and $1$-phenyl ethane$-1$-one?

In the given reaction,
$Cyclohexanone \xrightarrow[(ii) \text{ heat}]{(i) \text{ } OH^-} 'P'$
The number of $\pi$ electrons present in the product $'P'$ is $....$

Addition of alcohols to aldehydes in the presence of anhydrous acids yields: