Chemistry MCQs for NEET — Practice Questions with Answers

When a primary amine reacts with chloroform in the presence of ethanolic KOH, the product is an isocyanide. This reaction is known as the Carbylamine reaction or Hofmann's isocyanide test. The reaction can be represented as: $$ R-NH_2 + CHCl_3 + 3KOH ightarrow R-NC + 3KCl + 3H_2O $$

Intermolecular hydrogen bonding is strongest in methanol compared to methylamine, phenol, and methanal. This is because methanol (CH3OH) has a hydroxyl group (-OH) which can form strong hydrogen bonds with other methanol molecules. The oxygen atom in the hydroxyl group is highly electronegative and can attract hydrogen atoms from neighboring molecules, forming strong hydrogen bonds.

$ CH_3 NH_3 ^+ Cl ^ -$ being asalt, undergoes almostcomplete dissociation, therefore, it has ahigh dissociation constant.

Aniline (C6H5NH2) is indeed less basic than p-toluidine (C6H4CH3NH2). The methyl group (-CH3) in p-toluidine is an electron-donating group that increases the electron density on the nitrogen atom, making it more willing to donate a pair of electrons. This increased electron density makes p-toluidine more basic compared to aniline. Both statements are true, and the reason provided in Statement 2 correctly explains Statement 1.

Primary aliphatic amines do not form highly stable alkyldiazonium salts. These salts are generally unstable and decompose easily, unlike aromatic diazonium salts, which are more stable. Statement 1 is false. Statement 2 is true because benzenediazonium chloride is soluble in water due to its ionic nature, while benzenediazonium fluoroborate is insoluble in water due to the presence of the large and less polarizable BF4- anion.

Statement 1 is true because p-nitroaniline is indeed a weaker base than p-toluidine due to the electron-withdrawing nature of the nitro group. Statement 2 is false because the electron-withdrawing -NO2 group actually makes p-nitroaniline a weaker base, not a stronger base.

Statement 1 is true because benzonitrile cannot be prepared by nucleophilic substitution of benzene due to the lack of a good leaving group on benzene. Statement 2 is also true because benzonitrile can be easily prepared via diazonium salt. However, Statement 2 is not a correct explanation for Statement 1, as the preparation method via diazonium salt is a separate fact and does not explain the inability to prepare benzonitrile via nucleophilic substitution of benzene.

Statement 1 is true because carboxylic acids are obtained by the hydrolysis of cyanide compounds, and ammonia is liberated in the process. Statement 2 is also true because primary amines are obtained by the reduction of cyanide compounds in the presence of $LiAlH_4$. However, Statement 2 is not a correct explanation for Statement 1, as they describe two different reactions involving cyanide compounds.