Amines

37 solved questions from Class 12 Chemistry, each with the full working. Tap any question to see the step-by-step solution.

• 1 What is the primary chemical reaction or bonding mechanism highlighted in 'Amines' (Class 12)? medium MCQ Reaction Mechanism & Bonding
• 2 What factor affects the rate or equilibrium constant of reactions in 'Amines'? medium MCQ Chemical Kinetics & Factors
• 3 Which functional group or IUPAC nomenclature rule applies to compounds in 'Amines'? medium MCQ IUPAC Nomenclature & Structure
• 4 What is the major product obtained in the characteristic reaction of 'Amines'? medium MCQ Reaction Products & Selectivity
• 5 When excess aqueous ammonia reacts with ethyl bromide (CH_3CH_2Br) under reflux, which of the following is the major product? medium MCQ 1 mark Nucleophilic substitution of alkyl halides with ammonia
• 6 Methylamine (CH_3NH_2) is a weak base with K_b = 4.4 × 10^-4. Calculate the pH of a 0.10 M aqueous solution of methylamine at 25°C. easy 2 marks Basicity of aliphatic amines (pH calculation)
• 7 Explain why aliphatic primary amines are generally more basic than aniline. In your answer discuss the role of resonance and inductive effects, and indicate how these effects influence the K_b values. hard 5 marks Basicity comparison: aliphatic vs aromatic amines
• 8 Write the balanced overall chemical equation for the Hofmann rearrangement of benzamide (C_6H_5CONH_2) using sodium hypochlorite (NaOCl) and sodium hydroxide (NaOH). Also name the organic product formed. medium 3 marks Hofmann rearrangement of amides
• 9 Given the base dissociation constant K_b = 4.3 × 10^-10 for aniline at 25 °C, calculate its pK_a value. hard 3 marks Relation between $K_b$ and $pK_a$ for conjugate acid‑base pairs
• 10 Which reagent combination is used in the Gabriel synthesis to obtain a primary amine from an alkyl halide? easy MCQ 1 mark Gabriel synthesis of primary amines
• 11 Write the balanced overall chemical equation for the reduction of nitrobenzene to aniline using iron filings and hydrochloric acid. Also state the oxidation states of nitrogen in nitrobenzene and aniline. medium 2 marks Reduction of nitro compounds to amines
• 12 Explain the mechanism when a secondary amine reacts with nitrous acid. Include the formation of the N‑nitrosamine intermediate and why the reaction stops without forming a diazonium ion. State the final product. hard 4 marks Reaction of secondary amines with nitrous acid (formation of N‑nitrosamines)
• 13 Explain the mechanism of the Hofmann rearrangement when benzamide C_6H_5CONH_2 is treated with sodium hypochlorite (NaOCl) and sodium hydroxide (NaOH). Write the balanced overall chemical equation and name the organic product formed. hard 5 marks Hofmann rearrangement mechanism
• 14 When formaldehyde, dimethylamine, and acetophenone are mixed under acidic conditions, which compound is formed as the Mannich product? hard MCQ 3 marks Mannich reaction of amines
• 15 Among the following compounds, which one is a tertiary amine? easy MCQ 1 mark Classification of amines by substitution
• 16 Calculate the pH of a 0.20 M aqueous solution of diethylamine (CH_3CH_2)_2NH at 25°C. Given K_b=5.6×10^-4. medium 2 marks Basicity of aliphatic amines – pH calculation
• 17 What is the correct IUPAC name of the compound CH_3CH_2CH_2NH_2? easy MCQ 1 mark IUPAC naming of primary aliphatic amines
• 18 Calculate the pH of a 0.050 M aqueous solution of aniline (C_6H_5NH_2) at 25°C given K_b=4.3×10^-10. medium 2 marks pH calculation of weak base solution
• 19 Outline the Gabriel synthesis for preparing CH_3CH_2CH_2CH_2NH_2 (butylamine) from 1‑bromobutane. Include (i) the reaction of potassium phthalimide with 1‑bromobutane, (ii) the hydrolysis step using hydrazine hydrate, and (iii) write the overall balanced equation for the conversion of the phthalimide intermediate to butylamine. Also state the name of the key intermediate formed after the first step. hard 5 marks Gabriel synthesis of primary amines
• 20 In a Mannich reaction, 0.20 mol of formaldehyde, 0.20 mol of dimethylamine, and 0.15 mol of acetophenone are mixed under acidic conditions. After work‑up, 0.12 mol of the Mannich product (β‑amino carbonyl compound) is isolated. Calculate the percentage yield based on the limiting reagent. medium 2 marks Stoichiometry and yield in Mannich reaction
• 21 Write the overall balanced chemical equation for the conversion of benzyl bromide (C_6H_5CH_2Br) to benzylamine (C_6H_5CH_2NH_2) via the Gabriel synthesis. Also state the name of the intermediate formed after the first step. medium 2 marks Gabriel synthesis overall transformation
• 22 Choose the correct IUPAC name for the compound CH_3CH(NH_2)CH_2CH_3. easy MCQ 1 mark IUPAC naming of aliphatic primary amines
• 23 Calculate the pH of a 0.025 M aqueous solution of pyridine at 25°C given K_b=1.7×10^-9. medium 2 marks pH calculation of weak base solutions
• 24 Explain the mechanism of the Hofmann rearrangement when cyclohexanecarboxamide (C_6H_11CONH_2) is treated with sodium hypochlorite (NaOCl) and sodium hydroxide (NaOH). Write the balanced overall equation and give the name of the organic product formed. hard 5 marks Hofmann rearrangement mechanism
• 25 Outline the Gabriel synthesis for preparing phenethylamine C_6H_5CH_2CH_2NH_2 from phenethyl bromide C_6H_5CH_2CH_2Br. Include (i) the reaction of potassium phthalimide with the alkyl bromide, (ii) the hydrazine‑hydrate mediated hydrolysis, and (iii) write the overall balanced equation for the conversion of the phthalimide intermediate to phenethylamine. Also state the name of the intermediate formed after the first step. hard 3 marks Gabriel synthesis of primary amines
• 26 Calculate the pH of a 0.015 M aqueous solution of diethylamine ((CH_3CH_2)_2NH) at 25°C given K_b=5.6×10^-4. medium 2 marks Basicity of aliphatic amines
• 27 What is the correct IUPAC name of the compound CH_3CH_2CH_2CH_2NH_2? easy MCQ 1 mark Nomenclature of aliphatic primary amines
• 28 When cyclohexanecarboxamide C_6H_11CONH_2 is treated with sodium hypochlorite (NaOCl) and sodium hydroxide (NaOH), which of the following products is formed? hard MCQ 2 marks Hofmann rearrangement of aliphatic amides
• 29 In a Mannich reaction, 0.30 mol of formaldehyde, 0.25 mol of dimethylamine, and 0.20 mol of acetophenone are mixed under acidic conditions. After work‑up, 0.15 mol of the Mannich product is isolated. Calculate the percentage yield based on the limiting reagent. hard 3 marks Stoichiometry of Mannich reaction
• 30 Calculate the pH of a 0.020 M aqueous solution of pyridine at 25°C, given that K_b=1.7×10^-9. easy 2 marks pH calculation for weak base solution
• 31 What is the IUPAC name of the compound CH_3CH(NH_2)CH_2CH_3? easy 1 mark IUPAC nomenclature of aliphatic amines
• 32 Calculate the pH of a 0.030 M aqueous solution of pyridine at 25°C, given K_b=1.7×10^-9. medium 3 marks Basicity of pyridine and pH calculation
• 33 In a Mannich reaction, 0.40 mol of formaldehyde, 0.35 mol of piperidine, and 0.30 mol of acetophenone are mixed under acidic conditions. After work‑up, 0.20 mol of the Mannich product is isolated. Calculate the percentage yield based on the limiting reagent. hard 4 marks Stoichiometry and yield calculation in Mannich reaction
• 34 Which of the following compounds is the most basic at 25°C in aqueous solution? medium MCQ 2 marks Relative basicity of amines
• 35 In a Mannich reaction, 0.25 mol of formaldehyde, 0.30 mol of piperidine, and 0.20 mol of acetophenone are mixed under acidic conditions. After work‑up, 0.15 mol of the Mannich product is isolated. Calculate the percentage yield based on the limiting reagent. hard 4 marks Percent yield in Mannich reaction
• 36 Calculate the pH of a 0.040 M aqueous solution of triethylamine at 25°C, given K_b = 5.6×10^-4. medium 2 marks pH of weak base solution
• 37 Which of the following compounds is a primary aliphatic amine? (a) N,N-dimethylformamide (b) Pyridine (c) 2-Butylamine (d) Aniline easy MCQ 1 mark Primary aliphatic amines