Basic character of amines and the factors affecting it — NEET & JEE Questions

Question 1 · difficulty L1 · recall

The basic character of an amine is mainly due to

• A. the lone pair of electrons on nitrogen
• B. the presence of carbon only
• C. an N-H bond acting as a proton donor
• D. a permanent positive charge

Question 2 · difficulty L2 · understanding

Electron-releasing alkyl groups generally affect the basicity of amines by

• A. increasing electron density on nitrogen and tending to increase basicity
• B. removing the nitrogen lone pair
• C. making nitrogen positively charged before protonation
• D. having no electronic effect

Question 3 · difficulty L2 · understanding

Why is aniline generally less basic than methylamine?

• A. The nitrogen lone pair in aniline is delocalised into the benzene ring
• B. Aniline has no lone pair
• C. Methylamine is aromatic
• D. Aniline is permanently positively charged

Question 4 · difficulty L2 · understanding

An electron-withdrawing substituent on an aniline ring generally

• A. decreases basicity by reducing electron density available at nitrogen
• B. increases basicity in every case
• C. has no effect on the nitrogen lone pair
• D. converts the amine into an acid automatically

Question 5 · difficulty L3 · application

Which is generally more basic in aqueous solution: aniline or methylamine?

• A. Aniline
• B. Methylamine
• C. They are always exactly equal
• D. Neither can accept a proton

Question 6 · difficulty L3 · application

Which substituent on aniline would generally be expected to reduce its basicity most strongly among the following?

• A. $-CH_3$
• B. $-OCH_3$
• C. $-NO_2$
• D. $-C_2H_5$

Question 7 · difficulty L3 · application

Which compound is expected to be more basic because its nitrogen lone pair is not delocalised into an aromatic ring?

• A. Aniline
• B. Cyclohexylamine
• C. Nitrobenzene
• D. Phenol

Question 8 · difficulty L3 · application

If an amine accepts a proton to form $RNH_3^+$, what happened to the nitrogen lone pair?

• A. It was used to form a coordinate bond to the proton
• B. It was removed from the molecule
• C. It became a pi bond to carbon
• D. It was transferred entirely to a carbon atom

Question 9 · difficulty L4 · application

Which order is most reasonable for basicity based primarily on resonance effects?

• A. Cyclohexylamine > aniline
• B. Aniline > cyclohexylamine
• C. Phenol > cyclohexylamine
• D. Nitrobenzene > aniline

Question 10 · difficulty L4 · application

p-Nitroaniline is less basic than aniline mainly because

• A. the nitro group withdraws electron density and enhances delocalisation away from nitrogen
• B. the nitro group donates electrons strongly to nitrogen
• C. the amino group loses its lone pair completely
• D. the molecule has more atoms