Chemistry MCQs for NEET — Practice Questions with Answers

(a)      $R{\mathrm{NH}}_2 + {\mathrm{CHCl}}_3 + 3\mathrm{KOH}(\mathrm{alc}.) \stackrel{ }{\to } R\mathrm{NC} + 3\mathrm{KCl} + 3{\mathrm{H}}_2\mathrm{O}$

                                                                       Alkyl isocyanide

This reaction is known as carbylamone test.

(only $1°$ amine gives this reaction)

(d) Aliphatic amines are more basic than aromatic amines as the later are more stabilised due to resonance.

(d) 2,4-dinitro fluorobenzene is called Sanger's reagent. When this reagent reacts with amino group of peptide chain. It form 2,4-dinitrophenyl derivatives which on hydrolysis form DNP derivatives of amino acids.

In the Hofmann's reaction, an alkanamide undergoes rearrangement to form a primary amine with one less carbon atom. If the alkanamide gives 1-phenylethylamine on Hofmann's reaction, the starting alkanamide must be 2-phenylpropanamide.

(b) $R\mathrm{Br} + \mathrm{KCN} \stackrel{ }{\to }R\mathrm{CN} \stackrel{\mathrm{Reduction}}{\to } {\mathrm{RCH}}_2{\mathrm{NH}}_2$

(b) ${\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{NH}}_2\stackrel{{\mathrm{HNO}}_2}{\to }{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\stackrel{{\mathrm{PCl}}_5}{\to }{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Cl}\stackrel{{\mathrm{NH}}_3}{\to }{\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{NH}}_2$

(b) C₃H₈O is alcohol and C₃H₆O₂ is acid. Thus, C₃H₉N is primary amine.

(c) The reason for the less basic nature of amides.

(a) $R{\mathrm{CONH}}_2\stackrel{{\mathrm{P}}_2{\mathrm{O}}_5}{\to }R\mathrm{CN} + {\mathrm{H}}_2\mathrm{O}$