Which of the following reagents can distinguish between propanal and propanone?

Predict the product $C$ in the following series of reactions:

Identify the product $Y$ in the following reaction: $CH_3-CH=CH-CH_2-CHO + H_2 \xrightarrow{Ni} Y$

For making a distinction between $2$-pentanone and $3$-pentanone, the reagent to be employed is

Among the following,the number of compounds which will give positive iodoform reaction is:
$(a)$ $1-$Phenylbutan$-2-$one
$(b)$ $2-$Methylbutan$-2-$ol
$(c)$ $3-$Methylbutan$-2-$ol
$(d)$ $1-$Phenylethanol
$(e)$ $3,3-$dimethylbutan$-2-$one
$(f)$ $1-$Phenylpropan$-2-$ol

Which reagent is used to distinguish between acetaldehyde and acetophenone?