Which among the following compounds has the highest boiling point?

$A$ compound $(X)$ possesses a smell like bitter almond.
$(i)$ It does not give the Fehling test.
$(ii)$ It gives the silver mirror test.
$(iii)$ Compound $(X)$ gives orange precipitates of benzaldehyde $2,4-$dinitrophenylhydrazone with $2,4-DNP$.
Identify compound $(X)$ and provide its chemical reactions.

The product $(A)$ is:

In the Claisen$-$Schmidt reaction to prepare dibenzalacetone from $5.3 \ g$ benzaldehyde,a total of $3.51 \ g$ of product was obtained. The percentage yield in this reaction was $......... \%.$

$(A)$ and $(B)$ in the following reaction sequence are:
$RR'C=O$ $\xrightarrow{HCN} (A)$ $\xrightarrow{B} RR'C(OH)CH_2NH_2$

Comment on the stereochemistry of the products for the following reaction:
$3$-methylpentan-$2$-one + $CH_3MgBr$ followed by $NH_4Cl$ workup.