ISC Paper 2017
Chemistry
Maximum Marks: 70
Time allowed: 3 hours
- Answer all questions in Part I and six questions from Part II, choosing two questions from Section A, two from Section B and two from Section C.
- All working, including rough work, should be done on the same sheet as, and adjacent to, the rest of the answer.
- The intended marks for questions or parts of questions are given in brackets [ ].
- Balanced equations must be given wherever possible and diagrams where they are helpful.
- When solving numerical problems, all essential working must be shown.
- In working out problems use the following data:
Gas constant R = 1.987 cal deg-1 mol-1 = 8.314 JK-1 mol-1 = 0.0821 dm3 atm K-1 mol-1 . 1L atm = 1 dm3 atm = 101.3 J. 1 Faraday = 96500 Coulombs.
Avogadro’s number = 6.023 × 1023
Part – I (20 Marks)
Answer all questions.
Question 1.
(a) Fill in the blanks by choosing the appropriate word/words from those given in the brackets: [5]
(iodoform, acetaldehyde, positive, greater, acidic, acetone, disaccharide, negative, increases, glucose, decreases, chloroform, polysaccharide, lactose, lesser, basic, cationic hydrolysis, anionic hydrolysis)
(i) Calcium acetate on heating gives ………. which gives ……… on heating with iodine and sodium hydroxide solution.
(ii) On dilution of a solution, its specific conductance ……….. while its equivalent conductance ……….
(iii) Sucrose is a ………… and yields upon hydrolysis, a mixture of ………. and fructose.
(iv) More ………. the standard reduction potential of a substance, the ……… is its ability to displace hydrogen from acids.
(v) An aqueous solution of CH3COONa is ………. due to …………
(b) Complete the following statements by selecting the correct alternative from the choices given: [5]
(i) In a face-centred cubic lattice, atom (A) occupies the comer positions and atom (B) occupies the face centre positions. If one atom of (B) is missing from one of the face-centred points, the formula of the compound is:
(1) A2B5
(2) A2B3
(3) AB2
(4) A2B
Solution
Explanation:
(ii) The half-life period of a first-order reaction is 20 minutes. The time required for the concentration of the reactant to change from 0.16 M to 0.02 M is:
(1) 80 minutes
(2) 60 minutes
(3) 40 minutes
(4) 20 minutes
Solution
Explanation:
(iii) For a spontaneous reaction ΔG° and E° cell will be respectively:
(1) -ve and +ve
(2) +ve and -ve
(3) +ve and +ve
(4) -ve and -ve
Solution
Explanation:
(iv) The conjugate acid of HPO^{2-}_4 is:
(1) H3PO3
(2) H3PO4
(3){H_2PO^-_4}
(4){PO^{3-}_4}
Solution
Explanation:
(v) The polymer formed by the condensation of hexamethylenediamine and adipic acid is:
(1) Teflon
(2) Bakelite
(3) Dacron
(4) Nylon-66
Solution
Explanation:
(c) Answer the following questions: [5]
(i) Why the freezing point depression (ΔTf) of 0.4 M NaCl solution is nearly twice than that of 0.4 M glucose solution?
Solution
Explanation:
(ii) Identify the order of reaction from each of the following units of rate constant (k):
(a) mol L-1 sec-1
(b) mol-1 L sec-1
Solution
Explanation:
(iii) Specific conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm-1 . Calculate its molar conductivity.
Solution
Explanation:
(iv) Name the order of reaction which proceeds with a uniform rate throughout.
Solution
Explanation:
(v) What are the products formed when phenol and nitrobenzene are treated separately with a mixture of concentrated sulphuric acid and concentrated nitric acid?
Solution
Explanation:
(d) Match the following: [5]
i. | Diazotisation | Bakelite |
ii. | Argentite | Nernst equation |
iii. | Thermosetting plastics | Aniline |
iv. | Electrochemical cell | Ethylenediamine |
v. | Bidentate ligand | Froth floatation process |
Solution
Explanation:
Part – II (50 Marks)
Section – A
Answer any two questions.
Question 2.
(a) (i) Determine the freezing point of a solution containing 0.625 g of glucose (C6H12O6) dissolved in 102.8 g of water. [2]
(Freezing point of water = 273 K, Kf for water = 1.87 K kg mol-1 , at. wt. C = 12, H = 1, O = 16)
(ii) A 0.15 M aqueous solution of KCl exerts an osmotic pressure of 6.8 atm at 310 K. [2]
Calculate the degree of dissociation of KCl. (R = 0.0821 Lit. atm K-1 mol-1 ).
(iii) A solution containing 8.44 g of sucrose in 100 g of water has a vapour pressure 4.56 mm of Hg at 273 K. If the vapour pressure of pure water is 4.58 mm of Hg at the same temperature, calculate the molecular weight of sucrose. [1]
Solution
Explanation:
(b) (i) When ammonium chloride and ammonium hydroxide are added to a solution containing both Al3+ and Ca2+ ions, which ion is precipitated first and why? [2]
(ii) A solution of potassium chloride has no effect on litmus whereas, a solution of zinc chloride turns the blue litmus red. Give a reason. [2]
Solution
Explanation:
(c) How many sodium ions and chloride ions are present in a unit cell of sodium chloride crystal? [1]
Solution
Explanation:
Question 3.
(a) (i) Lead sulphide has a face-centred cubic crystal structure. If the edge length of the unit cell of lead sulphide is 495 pm, calculate the density of the crystal. [1]
(at. wt. of Pb = 207, S = 32)
(ii) For the reaction: , the following rate data was obtained: [3]
S.No. | [NO] mol L-1 | [H2] mol L-1 | Rate : mol L-1 sec-1 |
1 | 0.40 | 0.40 | 4.6 x 10-3 |
2 | 0.80 | 0.40 | 18.4 x 10-3 |
3 | 0.40 | 0.80 | 9.2 x 10-3 |
Calculate the following:
(1) The overall order of a reaction.
(2) The rate law.
(3) The value of rate constant (k).
Solution
Explanation:
(b) (i) The following electrochemical cell is set up at 298 K: [2]
(1) Write the cell reaction.
(2) Calculate the emf and free energy change at 298 K.
Solution
Explanation:
(a) Answer the following: [2]
(1) What is the effect of temperature on the ionic product of water (Kw)?
(2) What happens to the ionic product of water (Kw) if some acid is added to it?
Solution
Explanation:
(c) Frenkel defect does not change the density of the ionic crystal whereas, Schottky defect lowers the density of ionic crystal. Give a reason; [2]
Solution
Explanation:
Question 4.
(a) (i) Name the law or principle to which the following observations confirm: [3]
(1) When water is added to a 1.0 M aqueous solution of acetic acid, the number of hydrogen ion (H+) increases.
(2) When 9650 coulombs of electricity is passed through a solution of copper sulphate, 3.175 g of copper is deposited on the cathode (at. wt. of Cu = 63.5).
(3) When ammonium chloride is added to a solution of ammonium hydroxide, the concentration of hydroxyl ion decreases.
(ii) What is the difference between the order of a reaction and its molecularity? [2]
Solution
Explanation:
(b) (i) Explain why high pressure is required in the manufacture of sulphur trioxide by the contact process. State the law or principle used. [2]
(ii) Calculate the equilibrium constant (Kc) for the formation of NH3 in the following reaction: [ 1]
{N_2(g)+3H_2(g) \ \rightleftharpoons 2NH_3(g)}
At equilibrium, the concentration of NH3, H2 and N2 are 1.2 × 10-2 , 3.0 × 10-2 and 1.5 × 10-2 M respectively.
Solution
Explanation:
(c) Explain the following: [2]
(i) Hydrolysis of ester (ethyl acetate) begins slowly but becomes fast after some time.
(ii) The pH value of acetic acid increases on the addition of a few drops of sodium acetate.
Solution
Explanation:
Section – B
Answer any two questions.
Question 5.
(a) Write the formula of the following compounds: [2]
(i) Potassium trioxalatoaluminate (III).
(ii) Hexaaquairon (II) sulphate.
Solution
Explanation:
(b) Name the types of isomerism shown by the following pairs of compounds: [1]
(i) [CU(NH3)4] [PtCl4] and [Pt(NH3)4] [CuCl4]
(ii) [Co(Pn)2Cl2]+ and [Co(en)2Cl2]+
Solution
Explanation:
(c) For the coordination complex ion [Co(NH3)6]3+ [2]
(i) Give the IUPAC name of the complexion.
(ii) What is the oxidation number of cobalt in the complexion?
(iii) State the type of hybridisation of the complexion.
(iv) State the magnetic behaviour of the complexion.
Solution
Explanation:
Question 6.
(a) Give balanced equations for the following reactions: [3]
(i) Potassium permanganate is heated with concentrated hydrochloric acid.
(ii) Lead sulphide is heated with hydrogen peroxide.
(iii) Ozone is treated with potassium iodide solution.
Solution
Explanation:
(b) Discuss the theory involved in the manufacture of sulphuric acid by the contact process. [2]
Solution
Explanation:
Question 7.
(a) (i) What are the types of hybridisation of iodine in interhalogen compounds IF3, IF5 and IF7, respectively? [3]
(ii) Draw the structure of xenon hexafluoride (XeF6) molecule and state the hybridisationof the central atom.
Solution
Explanation:
(b) Give the balanced equations for the conversion of argentite (Ag2S) to metallic silver. [2]
Solution
Explanation:
Section – C
Answer any two questions.
Question 8.
(a) How can the following conversions be brought about:
(i) Acetaldehyde to propan-2-ol. [1]
(ii) Nitrobenzene to p-aminoazobenzene. [1]
(iii) Acetic acid to methylamine. [2]
(iv) Aniline to benzene. [1]
Solution
Explanation:
(b) (i) How will you distinguish between primary, secondary and tertiary amines by Hinsberg’s test? [1]
(ii) Why do alcohols possess higher boiling points as compared to those of corresponding alkanes? [1]
Solution
Explanation:
(c) Identify the compounds A, B and C: [3]
(i) {C_6H_5COOH {\overset {\ PCL_5}{\longrightarrow}} A \ {\overset {\ H_2-Pd/BaSO_4}{\longrightarrow}} B \ {\overset {\ KCN alc.}{\longrightarrow}} C}
(ii) {H-C \equiv C-H \ \underset{dil.\ H_2SO_4 + HgSO_4}{\overset{H_2O}{\longrightarrow}}A \underset{[Ni]}{\overset{H_2}{\longrightarrow}}B \underset{conc. \ H_2SO_4}{\overset{140^ o C}{\longrightarrow}}C}
Solution
Explanation:
Question 9.
(a) Give balanced equations for the following name reactions: [3]
(i) Friedel-Crafts reaction (alkylation)
(ii) Williamson’s synthesis
(iii) Aldol condensation
Solution
Explanation:
(b) Give the chemical test to distinguish: [3]
(i) Ethyl alcohol and sec-propyl alcohol
(ii) Acetaldehyde and acetic acid
Solution
Explanation:
(c) (i) Deficiency of which vitamin causes the following diseases: [4]
(1) Scurvy
(2) Night blindness
(ii) Write two differences between globular and fibrous proteins.
Solution
Explanation:
Question 10.
(a) An aliphatic unsaturated hydrocarbon (A) when treated with HgSO4/H2SO4 yields a compound (B) having molecular formula C3H6 O. (B) on oxidation with concentrated HNO3 gives two compounds (C) and (D). Compound (C), when treated with PCl5, gives compound (E). (E) when reacts with ethanol gives a sweet-smelling liquid (F).Compound (F) is also formed when (C) reacts with ethanol in the presence of concentrated H2SO4. [4]
(i) Identify the compounds A, B, C, D, E and F.
(ii) Give the chemical equation for the reaction of (C) with chlorine in the presence of red phosphorus and name the reaction.
Solution
Explanation:
(b) Answer the following: [3]
(i) What is the common name of the polymer obtained by the polymerisation of caprolactam? Is it addition polymer or condensation polymer?
Solution
Explanation:
(a) Name the two organic compounds which have the same molecular formula C2H6O. Will they react with PCl5? If they react, what are the products formed?
Solution
Explanation:
(c) Give balanced equations for the following reactions: [3]
(i) Methyl magnesium bromide with ethyl alcohol.
(ii) Acetic anhydride with phosphorus pentachloride.
(iii) Acetaldehyde with hydroxylamine.
Solution
Explanation: