How many compounds among the following give white crystals when reacted with sodium bisulphite $(NaHSO_3)$?
$1. HCHO$
$2. CH_3CHO$
$3. CH_3COCH_3$
$4. C_6H_5COCH_3$
$5. C_6H_5COC_6H_5$

Primary aldehyde on oxidation gives

Aldol condensation will not take place in

Which of the following products is formed when benzaldehyde is treated with $CH_3MgBr$ and the addition product so obtained is subjected to acid hydrolysis?

Given below are two statements: Consider the following reaction: $R_2C=O + H_2O \rightleftharpoons R_2C(OH)_2$.
Statement $I$: In the case of formaldehyde $(HCHO)$,$K_{eq}$ is about $2280$,due to small substituents,hydration is faster.
Statement $II$: In the case of trichloroacetaldehyde $(CCl_3CHO)$,$K_{eq}$ is about $2000$ due to the $-I$ effect of $-Cl$ atoms.
In the light of the above statements,choose the correct answer from the options given below:

Which compound can reduce Fehling reagent?