Chemistry MCQs for NEET — Practice Questions with Answers

The NCERT text explicitly states, 'This process of cleavage of the C–X bond by ammonia molecule is known as ammonolysis. ... The primary amine thus obtained behaves as a nucleophile and can further react with alkyl halide to form secondary and tertiary amines, and finally quaternary ammonium salt.'

The NCERT states, 'Ammonolysis has the disadvantage of yielding a mixture of primary, secondary and tertiary amines and also a quaternary ammonium salt. However, primary amine is obtained as a major product by taking large excess of ammonia.'

The NCERT states, 'Nitro compounds are reduced to amines by passing hydrogen gas in the presence of finely divided nickel, palladium or platinum and also by reduction with metals in acidic medium. Reduction with iron scrap and hydrochloric acid is preferred because FeClâ‚‚ 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 mentions, 'Nitriles on reduction with lithium aluminium hydride (LiAlHâ‚„) 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 NCERT states, 'The order of reactivity of halides with amines is RI > RBr > RCl.' This indicates that alkyl iodides are the most reactive.

The NCERT explains that ammonolysis (reaction of alkyl halides with ethanolic NH₃) 'has the disadvantage of yielding a mixture of primary, secondary and tertiary amines and also a quaternary ammonium salt.'

The introductory text states, 'Two biologically active compounds, namely adrenaline and ephedrine, both containing secondary amino group, are used to increase blood pressure.'

The NCERT states, 'pKb value of ammonia is 4.75. Aliphatic amines are stronger bases than ammonia due to +I effect of alkyl groups leading to high electron density on the nitrogen atom. Their pKb values lie in the range of 3 to 4.22.' A smaller pKb value indicates a stronger base.

The NCERT states, 'Reduction with iron scrap and hydrochloric acid is preferred because FeClâ‚‚ 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, 'Like ammonia, nitrogen atom of amines is trivalent and carries an unshared pair of electrons. Nitrogen orbitals in amines are therefore, sp³ hybridised and the geometry of amines is pyramidal.'