Time : Two hours Max. Marks : 60
1. The Question Paper has 4 printed pages and has 12 questions. Please ensure that the copy of the Question Paper you have received contains all the questions.
2. Attempts ALL questions. Each question carries 5 marks.
3. Answer each question starting on a new page. The corresponding Question number must be written in the left margin.
4. Do not write more than one answers for the same question. In case you attempt a question more than once, please cancel the answer(s) you consider to be wrong. Otherwise, only the answer appearing last will be evaluated.
5. Use only Arabic numerals (0, 1, 2 .............9) in answering the questions irrespective of the language in which your answer.
6. Use of logarithmic tables is NOT PERMITTED.
7. Use of calculators is NOT PERMITTED.
8. Both magnitude and direction of vector quantities, if any, in your answer should be indicated clearly.
9. Irrational numbers, if any, in your answer need not be expressed in decimal form.
10. If the final answer appears in the form of a ratio or a product of two numbers, that need not to be further simplified.
1. Five isomeric para-disubstituted aromatic compounds A to E with molecular formula C8H8O2 were given for identification. Based on the following observation, give structures of the compounds.
(i) Both A and B from a silver mirror with Tollen's reagent; also, B gives a positive test with FeCI3 solution.
(ii) C gives positive idoform test.
(iii) D is readily extracted in aqueous NaHCO3 solution.
(iv) E on acid hydrolysis gives 1, 4-dihydroxybenzene.
2. 500 mL of 0.2 M aqueous solution of acetic acid is mixed with 500 mL of 0.2 M HCI at 250oC.
(i) Calculate the degree of dissociation of acetic acid in the resulting solution and pH of the solution.
(ii) If 6 g of NaOH is added to the above solution, determine the final pH. [Assume there is no change in volume on mixing; Ka of acetic acid is
1.75 × 10-5 mol L-1].
3. Deduce the structures of [NiCI4]2- and [Ni(CN)4]2- considering the hybridization of the metal ion. Calculate the magnetic moment (spin only) of the species.
4. The density of the vapour of a substance at 1 atm pressure and 500 K is 0.36 kg m-3. The vapour effuses through a small hole at a rate of 1.33 times faster than oxygen under the same condition.
(a) Determine (i) molecular weight, (ii) molar volume, (iii) compression factor (Z) of the vapour and (iv) which forces among the gas molecules are dominating, the attractive or the repulsive?
(b) If the vapour behaves ideally at 1000 K, determine the average translational kinetic energy of a molecule.
5. Write balanced equations for the reactions of the following compounds with water:
6. Identify X, Y and Z in the following synthetic scheme and write their structures.
[i] NaNH2 H2/Pd BaSO4 alkaline KMnO2
CH3CH2C ≡ C - H -------------> X -------------> Y ----------------> Z
Is the compound Z optically active? Justify your answer.
7. How is boron obtained from borax? Give chemical equations with reaction conditions. Write the structure of B2H6 and its reaction with HCI.
8. 64Cu (half-life = 12.8 h) decays by b- emission (38%), b+ emission (19%) and electron capture (43%). Write the decay products and calculate partial half-lives for each of the decay processes.
9. When a white crystalline compound X is heated with K2Cr2O7 and concentrated H2SO4 a reddish brown gas A is evolved. On passing A into caustic soda solution, a yellow coloured solution of B is obtained. Neutralizing the solution of B with acetic acid and on subsequent addition of lead acetate a yellow precipitate C is obtained. When X is heated with NaOH solution, a colourless has is evolved and on passing this gas into K2HgI4 solution, a reddish brown precipitate D is formed. Identify A, B, C, D and X. Write the equations of reactions involved.
10. Write the structures of the products A, B, C, D and E in the following scheme.
11. A biologically active compound, Bombykol (C16H30O) is obtained from a natural source. The structure of the compound is determine by the following reactions.
(a) On hydrogenation, Bombykol gives a compound A, C16H34O, which reacts with acetic anhydride to give an ester,
(b) Bombykol also reacts with acetic hydride to give another ester, which on oxidative ozonolysis (O3/H2O2) gives a mixture of butanoic acid, oxalic acid and 10-acetoxy decanoic acid.
Determine the number of double bonds in Bombykol. Write the structures of compound A and Bombykol. How many geometrical isomers are possible for Bombykol?
12. Two moles of a perfect gas undergo the following processes:
(a) a reversible isobaric expansion from (1.0 atm, 20.0 L) to (1.0 atm, 40.0 L);
(b) a reversible isochoric change state from (1.0 atm, 40.0 L) to (0.5 atm, 40.0 L);
(c) a reversible isothermal compression from (0.5 atm, 40.0 L) to (1.0 atm, 20.0 L);
(i) Sketch with labels each of the processes on the same P-V diagram.
(ii) Calculate the total work (w) and the total heat change (q) involved in the above processes.
(iii) What will be the values of DU, DH and DS for the overall process?