How the following conversions takes place?

Acetophenone $\to$ Acetophenone cyanohydrin

How the following conversion takes place?

Give the structure of the carbonyl compound and amine used to form the following imines.

Give the structure of the carbonyl compound and amine used to form the following imines:

Predict the product of following aldol condensation reaction:

Predict the product of following aldol condensation reaction:

Indicate the starting aldehyde or ketone from which, the following compound is formed by an aldol condensation reaction:

$2-$Ethyl$-3-$hydroxy hexanal

Indicate the starting aldehyde or ketone from which, the following compound is formed by an aldol condensation reaction:

$4-$Hydroxy$-4-$methyl$-2-$pentanone

Predict the products of the following cross condensation reaction: