THE INDIAN COMMUNITY SCHOOL, KUWAIT SERIES : II SE / 2016-2017 CODE : N 043 MAX. MARKS : 70 TIME ALLOWED : 3 HOURS NO. OF PAGES : CHEMISTRY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1 mark questions 1. Why do amines react as nucleophiles? 2. Arrange the following in increasing order of basic strength: Aniline, p-nitro aniline, p-toluidine 3. Name the product of hydrolysis of Lactose. 4. Write the structure of the polymer PVC. 5. Write IUPAC name of K 3[Fe (C 2O 4) 3 ] 2 marks questions 6. How would you account for the following: a. Aldehydes are more reactive than Ketones towards nucleophiles. b. The boiling point of aldehydes and Ketones are lower than that of corresponding acids. 7. Complete the following reaction equations: a. C 6H 5N 2Cl + H 3PO 2 + H 2O ------> b. C 6H 5 NH 2 + Br 2 (aq) --------> 8. Give reasons for the following: a. Transition elements generally form coloured compounds. b. Zinc is not regarded as a transition element. a. Mn (II) ion shows maximum paramagnetic character among the bivalent ions of the first transition series. b. Scandium (At. No. 21) salts are white. 9. Name an important alloy which contains some lanthanoid metals. Mention it use. 10. Draw the structures of stereoisomers of the following coordination entities: a. [Cr ( C 2O 4 ) 3 ] 3- b. [Co (NH 3) 3Cl 3 ] 3 marks questions: 11. How would you obtain the following: a. But-2-en-1-al from ethanal b. Butanoic acid from butanol 12. Account for the following: a. Diazonium salts of aromatic amines are more stable than aliphatic amines. b. Aromatic amines are weaker bases than ammonia c. Ammonolysis of alkyl halide is not a suitable method to prepare pure primary amines. 13. Illustrate the following reactions: a. A coupling reaction b. Hoffmann s bromamide reaction c. Gabriel phthalimide reaction 14. What will happen when D-Glucose is treated with the following reagents? (write reaction) a. HI b. Bromine water c. HNO 3
15. Name one fat soluble vitamin, its source and the disease caused due to its deficiency in diet. 16. Explain the following terms: a. Invert sugar b. Glycoside linkage c. Denaturation of protein 17. a. Mention the optimum conditions for the industrial manufacture of ammonia by Haber s process. b. Give appropriate reasons for the following: i. Sulphur vapour exhibits paramagnetic behaviour. ii. Red Phosphorus is less reactive than white phosphorus. Account for the following : i. Nitrogen does not form pentahalides. ii. The two oxygen-oxygen bond lengths in ozone (O 3) molecule are same. iii. ICl is more reactive than I 2. 18. What are addition polymers. Name the two types of addition polymers. Give one example of each. 19. Write the names of the monomers of the following polymers i. Buna-S ii. Dacron iii. Neoprene 20. What are biodegradable polymers? Mention two uses of polymer PHBV. 21. Explain the following with an example each: i. Cationic detergents ii. Food preservatives iii. Analgesics 22. For the complex [Fe (H 2O) 6] 2+ identify the following: hybridisation, shape of the complex, Magnetic behaviour of the complex. 4 marks question 23. Natural sweeteners add to calorie intake and therefore cannot be used by diabetic patients. Such people use artificial sweeteners. i. Why is the use of aspartame limited to cold food and soft drinks? ii. What is the drawback of alitame? iii. What are the values possessed by people who control their sugar intake? 5 marks questions 24. a. Write chemical equations o illustrate the following reactions: i. Cannizzaro s reaction ii. Hell-Volhard Zelinsky reaction b. Give chemical tests to distinguish between the following pair of compounds: i. Propanal and Propanone ii. Acetophenone and Benzophenone iii. Phenol and Benzoicacid An organic compound with molecular formula C 8H 8O forms an orange red precipitate with 2,4-DNPreagent and give yellow precipitate on heating with iodine in the presence of sodium hydroxide. It neither reduces Tollens s reagent or Fehling s reagent nor does it decolourise Bromine water. On drastic oxidation with Chromic acid it gives a carboxylic acid (B) having molecular formula C 7H 6O 2. Identify the compounds A and B and explain the reactions involved.
25. a. Draw the structures of the following: XeF 4, H 2SO 4 b. Explain the following observations: i. Phosphorus has a greater tendency for catenation than nitrogen. ii. The negative value of electron gain enthalpy is less for Fluorine than that of Chlorine. iii. Hydrogen fluoride has a much higher boiling point than hydrogen chloride. a. What happens when : ( Write balanced chemical equations) i. Chlorine gas is passed through a hot concentrated solution of NaOH. ii. Sulphur dioxide is passed through an aqueous solution of a Fe(III) salt. b. Answer the following: i. What is the basicity of H 3PO 3? ii. Why does Fluorine not play the role of a central atom in interhalogen compounds? iii. Why do nobel gases have very low boiling point? 26. i. How will you prepare KMnO 4 from MnO 2? ii. Complete the following equation and balance them: a. Fe 2+ + MnO 4 - + H + ------> b. C 2 O 4 2- + MnO 4 - + H + ---------> i. How will you prepare Potassium dichromate from Sodium chromate? ii.what is the effect of increasing ph on a solution of Potassium dichromate? Write equation. iii. Draw the structure of Chromate ion.
CLASS XII CHEMISTRY II SEMESTER EXAMINATION ANSWER KEY Chemistry (marks 70; 3 hours) 1 mark questions 1. Why do amines react as nucleophiles? A. Due to presence of lone pair of electrons. 2. Arrange the following in increasing order of basic strength: Aniline, p-nitro aniline, p-toluidine A. p-nitroaniline < aniline < p-toludine 3. Name the product of hydrolysis of Lactose. A. Glucose and galactose 4. Write the structure of the polymer PVC. A. Correct structure 5. Write IUPAC name of K 3[Fe (C 2O 4) 3 ] A. Potassiumtrioxalatoferrate(III) 2 marks questions 6. How would you account for the following: a. Aldehydes are more reactive than Ketones towards nucleophiles. A. Two alkyl groups present in ketones offer steric hindrance to the incoming nuclephile. b. The boiling point of aldehydes and Ketones are lower than that of corresponding acids. A.This is because Carboxylic acid molecules are associated through intermolecular H-bonding. 7. Complete the following reaction equations: a. C 6H 5N 2Cl + H 3PO 2 + H 2O ------> Benzene b. C 6H 5 NH 2 + Br 2 (aq) -------->2,4,6-tribromoaniline 8. Give reasons for the following: a. Transition elements generally form coloured compounds. A. This is due to the presence of unpaired electron in d-orbitals. They undergo d-d transition. b. Zinc is not regarded as a transition element. A. This is because Zn and Zn 2+ have completely filled d orbital.
a. Mn (II) ion shows maximum paramagnetic character among the bivalent ions of the first transition series. A. Due to presence of 5 unpaired electrons. b. Scandium (At. No. 21) salts are white. A. Due to the absence of unpaired electrons d-d transition does not take place. 9. Name an important alloy which contains some lanthanoid metals. Mention it use. A. Misch metal. It is used in Mg based alloy to produce bullets. 10. Draw the structures of stereoisomers of the following coordination entities: a. [Cr ( C 2O 4 ) 3 ] 3- A.Correct structure b. [Co (NH 3) 3Cl 3 ] A.Correct structure 3 marks questions: 11. How would you obtain the following: a. But-2-en-1-al from ethanal ( by Aldol condensation) b. Butanoic acid from butanol (using strong oxidizing agent like KMnO 4) 12. Account for the following: a. Diazonium salts of aromatic amines are more stable than aliphatic amines. A. Due to resonance. b. Aromatic amines are weaker bases than ammonia. A.Due to electron withdrawing nature of aryl group. c. Ammonolysis of alkyl halide is not a suitable method to prepare pure primary amines. A. It gives a mixture of products difficultto separate. 13. Illustrate the following reactions: a. A coupling reaction Correct equations b. Hoffmann s bromamide reaction c. Gabriel phthalimide reaction 14. What will happen when D-Glucose is treated with the following reagents? ( write reaction) a. HI : n-hexane is formed (with equation) b. Bromine water : Gluconic acid is formed (with equation)
c. HNO 3 : Saccharic acid is formed (with equation) 15. Name one fat soluble vitamin, its source and the disease caused due to its deficiency in diet. A. Correct answer 16. Explain the following terms: a. Invert sugar: Hydrolysis of sucrose brings about change in sign of rotation from dextro to leavo and the product is called invert sugar. b. Glycoside linkage: A linkage between two monosaccharide units through oxygen atom. c. Denaturation of protein: Native protein loses its biological activity when subjected to physical change. 17. a. Mention the optimum conditions for the industrial manufacture of ammonia by Haber s process. A. Temperature around 700K, pressure around 200atm, iron oxide as catalyst with promoters. b. Give appropriate reasons for the following: i. Sulphur vapour exhibits paramagnetic behaviour. A. Due to presence of unpaired electrons in antibonding orbitals. ii. Red Phosphorus is less reactive than white phosphorus. A. As red phosphorus is polymeric. Account for the following : i. Nitrogen does not form pentahalides. A. Due to absence of d orbitals ii. The two oxygen-oxygen bond lengths in ozone (O 3) molecule are same. A.Due to resonance. iii. ICl is more reactive than I 2. A.Due to the weak I-Cl bond, bond dissociation enthalpy is very low. 18. What are addition polymers. Name the two types of addition polymers. Give one example of each. A. Correct answer 19. Write the names of the monomers of the following polymers i. Buna-S: 1,3-butadiene and Styrene ii. Dacron: Ethylene glycol and terephthalic acid iii. Neoprene: 2-Chloro-1,3-butadiene
20. What are biodegradable polymers? Mention two uses of polymer PHBV. A. Polymers which can be decomposed by by microorganisms. Uses: in speciality packaging orthopedic devices and in controlled release of drugs. 21. Explain the following with an example each: i. Cationic detergents: Quarternary ammonium salts of amines with acetates, chlorides or bromides. Eg. Cetyltrimethyl ammonium bromide ii. Food preservatives: They increase the shelf life of food. Eg.. sodium benzoate iii. Analgesics:They are drugs which reduce pain. Eg. Paracetamol 22. For the complex [Fe (H 2O) 6] 2+ identify the following: hybridisation, shape of the complex, Magnetic behaviour of the complex. A. Sp 3 d 2, Octahedral, paramagnetic 4 marks question 23. Natural sweeteners add to calorie intake and therefore cannot be used by diabetic patients. Such people use artificial sweeteners. i. Why is the use of aspartame limited to cold food and soft drinks? ii. What is the drawback of alitame? iii. What are the values possessed by people who control their sugar intake? 5 marks questions 24. a. Write chemical equations o illustrate the following reactions: i. Cannizzaro s reaction ii. Hell-Volhard Zelinsky reaction b. Give chemical tests to distinguish between the following pair of compounds: i. Propanal and Propanone (Iodoform test) ii. Acetophenone and Benzophenone (Iodoform test) iii. Phenol and Benzoicacid (neutral FeCl 3) An organic compound with molecular formula C 8H 8O forms an orange red precipitate with 2,4-DNPreagent and give yellow precipitate on heating with iodine in the presence of sodium hydroxide. It neither reduces Tollens s reagent or Fehling s reagent nor does it decolourise Bromine water. On drastic oxidation with Chromic acid it gives a carboxylic acid (B) having molecular formula C 7H 6O 2. Identify the compounds A and B and explain the reactions involved. A. Acetophenone. Proper reaction equations
25. a. Draw the structures of the following: XeF 4, H 2SO 4 b. Explain the following observations: i. Phosphorus has a greater tendency for catenation than nitrogen. A. As P-P bonds are strong. ii. The negative value of electron gain enthalpy is less for Fluorine than that of Chlorine. A. Due to small size of F incoming electron experiences repulsion. iii. Hydrogen fluoride has a much higher boiling point than hydrogen chloride. A.HF molecules are associated through intermolecular H bonding. a. What happens when : ( Write balanced chemical equations) i. Chlorine gas is passed through a hot concentrated solution of NaOH. A.6NaOH + 3Cl 2 -----> 5NaCl + NaClO 3 + 3H 2O A. 2Fe 3+ + SO 2 + 2H 2O ------> 2Fe 2+ 2- + SO 4 + 4H + b. Answer the following: i. What is the basicity of H 3PO 3? A.basicity is 2. ii. Why does Fluorine not play the role of a central atom in interhalogen compounds? A.Due to absence of d orbitals. iii. Why do nobel gases have very low boiling point? A. Due to weak vander waal forces. 26. i. How will you prepare KMnO 4 from MnO 2? ii. Complete the following equation and balance them: a. 5Fe 2+ - + MnO 4 + 8 H + ------>Mn 2+ + 4H 2O + 5Fe 3+ b.5 C 2 O 2- - 4 + 2MnO 4 + 16 H + ---------> 2Mn 2+ + 8H 2O + 10CO 2 i. How will you prepare Potassium dichromate from Sodium chromate? A. Correct equations ii.what is the effect of increasing ph on a solution of Potassium dichromate? Write equation. A.It changes to chromate ion. Correct equation. iii. Draw the structure of Chromate ion. A. correct structure.