Schiff's reagent gives pink colour with

What is the product obtained in the reaction of acetaldehyde with semicarbazide?

Fehling solution reacts with $HCHO$ to form a precipitate of which color?

Based on the reaction sequence shown,select the incorrect statement about $P_2$. The reaction starts with cyclohexanone reacting with $Mg-Hg/H_2O$ to form $P_1$,which then reacts with conc. $H_2SO_4$ and heat to form $P_2$.

$CH_3-CO-CH_3 + [O] \xrightarrow{SeO_2} P + Se + H_2O$. What is $P$ here?

Which of the following reagents should be used to carry out the above conversion $:-$
(Image shows the reduction of a ketone group to a secondary alcohol in the presence of an ester group)