(a) Write the product(s) in the following reactions:
(i) $+\mathrm{HCN}⟶?$
(ii)  $+\mathrm{NaOH}\underset{\mathrm{\Delta }}{\stackrel{\mathrm{CaO}}{⟶}?}$
(iii) ${\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CN}\underset{2}{\stackrel{ (\mathrm{a}) \mathrm{DIBAL}-\mathrm{H}}{⟶}}\mathrm{ ? }$
(b) Give simple chemical tests to distinguish between the following pairs of compounds :
(i) Butanal and Butan-2-one
(ii) Benzoic acid and Phenol

(a)
(i)
(ii)
(iii) ${\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CN}\frac{\text{ (a) DIBAL-H }}{\left(\mathrm{b}\right) {\mathrm{H}}_2\mathrm{O}}{\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}O$

(b) (i) Butanal and butan-2-one can be distinguished with Tollen’s test. Butanal gives positive test with Tollen's reagent while butan-2-one give negative test.

(ii) Benzoic acid gives a colored buff colored ppt with FeCl₃ solution while phenol fives violet color ppt with FeCl₃ solution.