(a) (i) Write the major product(s) in the following reactions: (2) (3) (ii) Give simple chemical tests to distinguish between the following pairs of…

Write the major product(s) in the following reactions :

Give simple chemical tests to distinguish between the following pairs of compounds :

and

Pentanal and Pentan-$\displaystyle 3$-one

Give reasons for the following :

In semicarbazide, only one $\displaystyle -\mathrm{NH}_{2}$ group is involved in the formation of semicarbazone.

Acetaldehyde is more reactive than acetone towards addition of HCN.

Arrange the following in decreasing order of their acidic strength : $\displaystyle \mathrm{CH}_{3} \mathrm{COOH}, \quad \mathrm{O}_{2} \mathrm{~N}-\mathrm{CH}_{2}-\mathrm{COOH}, \quad \mathrm{HCOOH}$

Name the reagent in the following reaction : \[\begin{aligned} \mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}- & \mathrm{CH}_{2}-\mathrm{CN} \xrightarrow{?} \\ & \mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CHO} \end{aligned} \]

Write the reaction involved in Hell-Volhard-Zelinsky reaction.