NEET Practice Questions (MCQs) with Answers & Solutions

The text explains: 'This intermolecular association is more in primary amines than in secondary amines as there are two hydrogen atoms available for hydrogen bond formation in it. Tertiary amines do not have intermolecular association due to the absence of hydrogen atom available for hydrogen bond formation.'

The context mentions: 'Reduction with iron scrap and hydrochloric acid is preferred because $FeCl_2$ formed gets hydrolysed to release hydrochloric acid during the reaction. Thus, only a small amount of hydrochloric acid is required to initiate the reaction.'

The NCERT text states: 'Ammonolysis has the disadvantage of yielding a mixture of primary, secondary and tertiary amines and also a quaternary ammonium salt.'

The text says: 'However, primary amine is obtained as a major product by taking large excess of ammonia.'

The text states: 'Nitriles on reduction with lithium aluminium hydride ($LiAlH_4$) or catalytic hydrogenation produce primary amines. This reaction is used for ascent of amine series, i.e., for preparation of amines containing one carbon atom more than the starting amine.'

The context explains: 'Lower aliphatic amines are soluble in water because they can form hydrogen bonds with water molecules.'

The context provides a hint: 'Considering the electronegativity of nitrogen of amine and oxygen of alcohol as 3.0 and 3.5 respectively, you can predict the pattern of solubility of amines and alcohols in water.' And then it explicitly states: 'You may remember that alcohols are more polar than amines and form stronger intermolecular hydrogen bonds than amines.' Stronger hydrogen bonding with water implies better solubility.

The text mentions: 'Aniline and other arylamines are usually colourless but get coloured on storage due to atmospheric oxidation.'

The text clearly states: 'Moreover, amines behave as nucleophiles due to the presence of unshared electron pair.'

The NCERT table (Table 9.3) provides $pK_b$ values. A smaller $pK_b$ value indicates a stronger base. Among the given options, N-Ethylethanamine has the lowest $pK_b$ of 3.00.