Identify an aldehyde used in margarine and in food for its buttery odour.

What type of following compounds is obtained in first step of Wolf-Kishner reduction of carbonyl compounds?

What is the product obtained in the reaction?

$\mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2-\mathrm{CHO} \xrightarrow[\text { (i) } \mathrm{H}_3 \mathrm{O}^{+}]{\text {(i) } \mathrm{LAH}_4}$ product

Which of the following compounds is used to convert acetaldehyde into acetaldehyde cynanohydrin?