PAPER- 1 PART-A Select the correct alternative. (Only one is correct) [99 × 3 = 297] There is NEGATIVE marking. 1 mark will be deducted for each wrong answer. Q.34 20 ml of 0.05 M solution of the conjugate acid of an -amino acid methionine (H2A+) is taken. The pka of –COOH group in methionine is 2.8 and pkb of basic group is 4.8. Pick out only incorrect statement among the following. [Use log 2 = 0.3] (A) pH of original amino acid solution was ~ 2.05 (B) pH of solution was ~ 2.8 when 10 ml 0.05 M NaOH solution is added to original solution (C) pH of solution is ~ 6 when 20 ml 0.05 M NaOH solution is added to original solution (D*) pH of solution is 3.8 when 20 ml 0.05 M NaOH solution is added to original solution Q.35 Which of the following compound(s) will give blue colour when it is converted into Lassaigne's extract and FeSO4 is added followed by FeCl3. (I) (II) (III) CH3–NMe2 (IV) NH2–NH2 (A*) III only (B) II & III (C) II, III & IV (D) I, II, III & IV Q.36 ZnO shows yellow colour on Heating due to (A) d–d transition (B) C–T spectra (C) Higher polarisation caused by Zn2+ ion (D*) F– centres Q.37 The decomposition of N2O5 in chloroform was followed by measuring the volume of O2 gas evolved : 2N2O5 (CCl4) 2N2O4 (CCl4) + O2(g). The maximum volume of O2 gas obtained was 100 cm3. In 500 minutes, 90 cm3 of O2 were evolved. The first order rate constant (in min–1) for the rate of disappearance of N2O5 is 2.303 (A*) 500 2.303 (B) 500 100 log 90 2.303 (C) 500 90 log 100 100 (D) 10 500 Q.38 What will be the order of rotation barriers about C–N bond among these compounds ? (I) CH3–CH2–NH2 (II) (III) (A) I > II > III (B*) I < II < III (C) II > III > I (D) III > I > II Q.39 Complex compound [Cr(NCS)(NH3)5] [ZnCl4] will be (A) Colourless & diamagnetic (B) Green coloured & diamagnetic (C*) Green coloured & shows coordination isomerism (D) Diamagnetic & shows linkage isomerism Q.40 The vapour pressure of pure perflourocyclohexane (C6F12) are given by the following equations: 1890 Solid C6F12 : log10 p(mm Hg) = 8.68 – T 1530 Liquid C6F12 : log10 p(mm Hg) = 7.60 – T The molar enthalpy of fusion of solid C6F12 is approximately (A*) 1658 cal (B) 360 cal (C) 3420 cal (D) 720 cal Q.41 + HNO3 + H2SO4 Product. Product is: (A*) (B) (C) (D) Both B & C Q.42 Which of the following is correct. (A) F2 has higher dissociation energy than Cl2 (B) F has higher electron affinity than Cl (C) HF is stronger acid than HCl (D*) Boiling point increases down the group in halogens Q.43 + – CH(R)– CO H has its Ka = 10–7. The isoelectric point of the -amino acid occur at pH = 8.2 N H3 2 1 hence pKa2 of the conjugate acid of -amino acid is equal to (A*) 9.4 (B) 1.2 (C) 7.6 (D) 2.4 Q.44 The product of I– with MnO in alkaline medium is (A) I2 (B*) IO (C) IO– (D) IO Q.45 Which of the following will racemize in presence of acid or base impurities in aqueous medium. CH3 | (A) Me C C Ph