Reduction of an aldehyde produces

Which of the following does not give a yellow precipitate with $I_2$ and $NaOH$?

Arrange the following compounds in decreasing order of reactivity towards nucleophilic addition reactions:
$(I) \ HCHO$,$(II) \ CH_3CHO$,$(III) \ CH_3COCH_3$,$(IV) \ CH_3CH_2COCH_2CH_3$

$RCH=O + H_2 \xrightarrow{\text{catalyst}} RCH_2OH$. Which catalyst is used for this reaction?

Which of the following compounds would undergo aldol condensation,which the Cannizzaro reaction and which neither? Write the structures of the expected products of aldol condensation and Cannizzaro reaction.
$(i)$ Methanal $(ii)$ $2-$Methylpentanal $(iii)$ Benzaldehyde $(iv)$ Benzophenone $(v)$ Cyclohexanone $(vi)$ $1-$Phenylpropanone $(vii)$ Phenylacetaldehyde $(viii)$ Butan$-1-$ol $(ix)$ $2,2-$Dimethylbutanal

Which product is obtained by the reduction of propionaldehyde with amalgamated zinc and concentrated $HCl$?