Which of the following is reduced by $Zn-Hg/HCl$ to give the corresponding hydrocarbon?

Aldol condensation involving $CH_3-CHO + CH_3-CHO$ gives the product:

Which of the following compounds does not react with $NaHSO_3$?

Draw structures of the following derivatives:
$(i)$ The $2,4-$dinitrophenylhydrazone of benzaldehyde
$(ii)$ Cyclopropanone oxime
$(iii)$ Acetaldehyde dimethyl acetal
$(iv)$ The semicarbazone of cyclobutanone
$(v)$ The ethylene ketal of hexan$-3-$one
$(vi)$ The methyl hemiacetal of formaldehyde

The number of aldehydes that undergo Cannizzaro reaction from the following are Phenyl ethanal,Methanal,$2-$Methoxy propanal,Trichloro ethanal.

What are the products formed in the following reaction?
$CH_3CH_2CHO + 2Cu^{2+} + 5OH^{-} \rightarrow X + Y + 3H_2O$