$4$-formylbenzoic acid on treatment with one equivalent of hydrazine followed by heating with alc. $KOH$ gives the major product:

Given below are two statements:
Statement $I$: Cross aldol condensation between two different aldehydes will always produce four different products.
Statement $II$: When semicarbazide reacts with a mixture of benzaldehyde and acetophenone under optimum pH, it forms a condensation product with acetophenone only.
In the light of the above statements, choose the correct answer from the options given below:

$Ph-CO-CH_3 \xrightarrow[H_2O]{Mg-Hg}$ Product. The main product is:

Which product is formed when the compound $C_6H_5CHO$ is treated with concentrated $KOH$ solution?

Identify the correct statements about $Z$ in the following reaction sequence:
$C_2H_5NH_2$ $\xrightarrow[NaNO_2 / HCl]{} X$ $\xrightarrow{H_2O} Y$ $\xrightarrow{Cu / 573 \ K} Z$
$I$. $Z$ is an aldehyde
$II$. $Z$ undergoes Cannizzaro reaction
$III$. $Z$ gives iodoform test
$IV$. $Z$ does not give test with Tollens' reagent

$OHC-CH_2-CH_2-CH_2-CH_2-CHO \xrightarrow{OH^{-} / \Delta} \text{Product } (A) \text{ is:}$