Chemistry MCQs for NEET — Practice Questions with Answers

Methylamine (CH₃NH₂) is a stronger base than ammonia (NH₃) due to the electron-donating effect of the methyl group. The methyl group increases the electron density on the nitrogen atom, making it more basic compared to ammonia.

Urea (CO(NH₂)₂) is the correct answer. When urea is treated with a mixture of sodium nitrite (NaNO₂) and dilute hydrochloric acid (HCl), it undergoes a reaction that generates nitrogen gas, causing brisk effervescence.

Aliphatic amines are soluble in water because of their ability to form hydrogen bonds with water molecules. The nitrogen atom in amines has a lone pair of electrons, which can form hydrogen bonds with the hydrogen atoms of water molecules.

 ${\mathrm{CH}}_3{\mathrm{NO}}_2 \underset{\mathrm{or} \mathrm{Sn}/\mathrm{HCl}}{\overset{\mathrm{Zn}/\mathrm{HCl}}{\to }}{\mathrm{CH}}_3{\mathrm{NH}}_2$

(d) ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{NO}}_2 \underset{\mathrm{Neutral} \mathrm{med}.}{\overset{\mathrm{Al}-\mathrm{Hg}/\mathrm{water}}{\to }}{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{NHOH}$

                                      Phenylhydroxylamine

(c) The conversion of -CN to -CH₂NH₂ by catalytic reduction is called Mendius reaction.

(c) Both gives alkane (RH) with Grignard reagents RMgX due to the presence of acidic hydrogen (N-H).

(a) $R-\mathrm{CN} \stackrel{\mathrm{Reduction}}{\to }R{\mathrm{CH}}_2{\mathrm{CH}}_2$

 Negative charge developed on N in the resonance hybride makes it more basic as it loses electron pair readily. Also $2°$ amine is more basic than $1°$ amine due to +ve IE of alkyl group. In amide, the lone pair remains less avaible due to delocalisation is resonance.

The reaction of a primary amine with carbon disulfide (CSâ‚‚) in the presence of excess mercuric chloride (HgClâ‚‚) to form an isothiocyanate is known as the Hofmann's mustard oil reaction. This reaction is used to synthesize isothiocyanates, which have a characteristic pungent odor.