Which of the following tests is $NOT$ shown by acetaldehyde?

The product which is not expected to be formed in the following reaction is:
$C_6H_5CHO + CH_3CH_2CHO \xrightarrow{OH^-(aq.), \Delta} \text{Product}$

If the enolate ion combines with the carbonyl group of an ester,we get:

$Ph-CH(OH)-CH_3$ $\xrightarrow{PCC} (A)$ $\xrightarrow{NH_2-NH-C(=O)-NH_2} (B)$. Product $(B)$ is:

The product $(Q)$ will be:

When acetaldehyde is heated with Fehling's solution,it gives a red precipitate of: