Amines Exam Questions PDF

Questions: 1. What is the general formula for a primary amine? * A) RNH2 * B) R2NH * C) R3N * D) R4N+ 2. What is the shape of the amine group in a primary amine? * A) Linear * B) Trigonal planar * C) Tetrahedral * D) Trigonal pyramidal 3. Which of the following describes the solubility of short-c...

Questions: 1. What is the general formula for a primary amine? * A) RNH2 * B) R2NH * C) R3N * D) R4N+ 2. What is the shape of the amine group in a primary amine? * A) Linear * B) Trigonal planar * C) Tetrahedral * D) Trigonal pyramidal 3. Which of the following describes the solubility of short-chain amines in water? * A) They are insoluble. * B) They are soluble * C) They react violently with water. * D) They are non-polar 4. Why are primary amines able to act as bases? * A) They can donate a proton. * B) They have a lone pair of electrons on the nitrogen atom that can accept a proton. * C) They have a positive charge. * D) They are strong oxidising agents. 5. Which of the following is the strongest base? * A) Ammonia * B) Phenylamine * C) Ethylamine * D) Water 6. Why is phenylamine a weaker base than ethylamine? * A) The phenyl group is electron-donating. * B) The lone pair on the nitrogen is delocalised into the benzene ring. * C) Phenylamine is more soluble in water. * D) Ethylamine is a smaller molecule. 7. What is the product when a primary amine reacts with a haloalkane? * A) A secondary amine * B) A tertiary amine * C) An ammonium salt * D) An alcohol 8. What is the product of the reduction of a nitrile using LiAlH4? * A) A primary amine * B) A secondary amine * C) A carboxylic acid * D) An amide 9. How can phenylamine be prepared from nitrobenzene? * A) Reduction using Sn and concentrated HCl * B) Oxidation using acidi ed potassium dichromate(VI) * C) Reaction with ammonia * D) Reaction with an acyl chloride 10. What is the product of the reaction between a primary amine and an acyl chloride? * A) A primary amide * B) A secondary amide * C) A tertiary amide * D) An ester 11. What is the name given to the product formed when ethylamine reacts with ethanoyl chloride? * A) N-ethylethanamide * B) N-methylethanamide * C) N,N-diethylethanamide * D) Ethylethanamide 12. What type of reaction occurs between a primary amine and an acyl chloride? * A) Nucleophilic substitution * B) Electrophilic substitution * C) Nucleophilic addition-elimination (Acylation) * D) Electrophilic addition fi 13. Which of these is a suitable reagent for ethanoylation? * A) Ethanoic acid * B) Ethanol * C) Ethanoyl Chloride * D) Ethyl Ethanoate 14. What are the reagents required to form a diazonium salt from phenylamine? * A) Sodium nitrate(III) and dilute hydrochloric acid, below 5°C * B) Sodium nitrate(V) and dilute hydrochloric acid, below 5°C * C) Sodium nitrate(III) and dilute hydrochloric acid, at room temperature * D) Sodium nitrate(V) and dilute hydrochloric acid, at room temperature 15. What is the formula of the benzenediazonium ion? * A) C6H5NH3+ * B) C6H5N2+ * C) C6H5NO2 * D) C6H5NH2 16. What is the name of the compound formed when a benzenediazonium ion reacts with phenylamine? * A) An azo dye * B) A carboxylic acid * C) An ester * D) An amide 17. Which of the following is true about azo dyes? * A) They are colourless. * B) They contain a -N=N- group. * C) They contain a -COOH group. * D) They are formed by reacting phenylamine with an acyl chloride. 18. Why does the benzenediazonium ion react with the carbon-4 on the phenylamine ring? * A) The amine group deactivates the ring. * B) The lone pair on the nitrogen increases the electron density at positions 2, 4, and 6. * C) The amine group is electron-withdrawing. * D) The benzenediazonium ion is a strong nucleophile. 19. What is the name given to the type of reaction between a diazonium ion and phenylamine? * A) Acylation * B) Coupling * C) Condensation * D) Hydrolysis 20. What is the name of the unstable compound that is produced *in situ* for the formation of a diazonium salt? * A) Nitric(V) Acid * B) Nitric (III) Acid * C) Hydrochloric Acid * D) Sodium Nitrate (V) 21. What conditions are required for the coupling reaction between a diazonium salt and phenol? * A) Acidic conditions * B) Alkaline conditions * C) Neutral conditions * D) Anhydrous conditions 22. Which of the following is a chromophore? * A) -COOH * B) -OH * C) -N=N- * D) -NH2 23. Why are some organic compounds coloured? * A) They absorb all wavelengths of visible light. * B) They absorb certain wavelengths of visible light and re ect others. * C) They re ect all wavelengths of visible light. * D) They do not interact with visible light. 24. What is the product when propylamine reacts with cold nitric(III) acid? * A) Propanol, nitrogen gas, and water * B) A diazonium salt * C) Propene, nitrogen gas, and water * D) No reaction fl fl 25. In terms of frequency, what can be said of light that is absorbed by a blue compound? * A) High Frequency * B) Low Frequency * C) The compound only absorbs low frequency light * D) The compound only absorbs high frequency light Answers and Explanations: 1. A - RNH2 2. D - Trigonal pyramidal (similar to ammonia). 3. B - Short chain amines can form hydrogen bonds with water. 4. B 5. C - Alkyl groups are electron-donating, increasing the availability of the lone pair. 6. B - Delocalisation makes the lone pair less available for accepting a proton. 7. A- A secondary amine and an ammonium salt as a by-product. 8. A - LiAlH4 is a strong reducing agent. 9. A - Tin (Sn) and concentrated HCl reduce the -NO2 group to -NH2. 10. B - A secondary amide is formed via nucleophilic addition-elimination (acylation). 11. A 12. C 13. C 14. A - Sodium nitrite (NaNO2) and HCl react to form HNO2 (nitric(III) acid) *in situ*. Low temperature is essential. 15. B 16. A - Azo dyes contain the -N=N- link between two benzene rings. 17. B - The -N=N- group is the chromophore. 18. B - The -NH2 group is activating and 2,4,6-directing. 19. B - Coupling reactions join two aromatic rings via an azo (-N=N-) link. 20. B - Nitric(III) acid, HNO2, is unstable and made *in situ*. 21. B - Alkaline conditions are required for phenol to form the phenoxide ion, which is more reactive. 22. C A chromophore is the part of a molecule that absorbs light. 23. B 24. A - Aliphatic amines react with cold nitrous acid to produce the alcohol, nitrogen gas, and water. 25. A - Because a blue compound is re ecting blue light (and absorbing other colours), it's absorbing light at the red end of the spectrum. Red light has lower frequency than blue light. Therefore, the blue compound is absorbing light *other than blue*. However, within that absorbed portion, there will be higher frequencies than the *re ected* blue light. The statement that best captures this subtlety is that the absorbed light, in comparison to the re ected blue, contains higher frequency components. fl fl fl