$3$-hydroxybutanal is formed when $(X)$ reacts with $(Y)$ in a dilute $(Z)$ solution. What are $X, Y$ and $Z$?

The major product of the following reaction is

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

Methyl ketone group is identified by

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents:
$(i)$ $PhMgBr$ and then $H_3O^{+}$
$(ii)$ Tollens' reagent
$(iii)$ Semicarbazide and weak acid
$(iv)$ Excess ethanol and acid
$(v)$ Zinc amalgam and dilute hydrochloric acid

In the reaction,
$C_6H_5COCl \xrightarrow[(ii) Y]{(i) X} C_6H_5CH=CHCOOH$
$X$ and $Y$ are