May 2011 - Career Point

6. Choose the INCORRECT statement from thefollowing(A) Hexagonal closest packed (HCP) and cubicclosest packed (CCP) structures havecoordination numbers of 12 and 7, respectively(B) HCP and CCP structures involve ABABABand ABCABCABC stacking, respectively(C) HCP and CCP structures involve the same netpacking density(D) Metals can crystallize in either HCP or CCPstructures, depending on the element7. C 60 (buckyball) is cubic closest packed (facecentredcubic) in its crystalline form. If you insertpotassium atoms into all the tetrahedral andoctahedral holes of the C 60 structure, the formulawould become K x C 60 . What is the value of x ?(A) 1 (B) 2 (C) 3 (D) NoneQuestions 8 to 11 are multiple choice questions. Eachquestions has four choices (A), (B), (C) and (D), out ofwhich MULTIPLE (ONE OR MORE) is correct.8. Which one of the following statements is (are) in aconcentration cell made of Fe in 0.010 M Fe 2+ (aq)and Fe in 0.10 M Fe 2+ (aq)?(A)The Eº cell = 0(B) ∆G = 0(C) The cell reaction is Fe 2+ (aq 0.010 M) →Fe 2+ (aq, 0.10 M)(D) At equilibrium, the [Fe 2+ ] anode = [Fe 2+ ] cathode9. The emf of a galvanic cell depends upon(A) surface area of electrodes(B) concentration of electrolyte(C) volume of electrolyte(D) temperature10. To 20 mL of 0.1 M barium chloride solution 0.2mL of 3 M chromium sulphate is added BaSO 4formed is completely insoluble and all the salts arecompletely dissociated (Change in volume isignored). Then,(A) boiling point is raised(B) boiling point is lowered(C) freezing point does not change(D) freezing point is increased11. An atomic solid has hexagonal arrangement of unitcell with height of hexagonal (in close packedarrangement) as "h" The radius of atom in terms ofheight is2(A) 4 h(B)3(C)h232(D)h4h42332This section contains 2 paragraphs, one has 3multiple choice questions and other has 2 multiplechoice questions (Question 12 to 16). Each questionshas 4 choices (A), (B), (C) and (D) out of which ONLYONE is correct.Passage : I (Q. No. 12 to 14)The structure of unit cell of perovskite – a salt oflanthanum(La), manganese (Mn) and oxygen, hasMn 2+ at the each corner, oxide on every edgecentre and a lanthanum ion at the body centre.12. What is the empirical formula of the salt?(A) LaMnO 2 (B) LaMn 2 O 3(C) LaMnO 3 (D) Both (B) and (C)13. What are the coordination ion numbers of Mn; Laand O, respectively?(A) 6, 2, 8 (B) 6, 4, 12(C) 8, 4, 8 (D) 6, 12, 214. Considering the closed packed arrangement of ions,which of the following statement regarding theionic radii is most the appropriate?(A) r 4+> r 2La O–(B) r 4+> r 2La Mn+(C) Edgelength of unit cell = r 2++ r 2Mn O–(D) None of the abovePassage : II (Q. No. 15 to 16)Properties such as vapour pressure, boiling point,freezing point of pure solvent changes when solutemolecules are added in order to preparehomogeneous solution. These are called colligativeproperties. Application of colligative properties arevery useful in day to day life. One of its examplesis the use of ethylene glycol and water mixture asanti-freezing agent in the radiator of automobiles. Asolution M is prepared by mixing ethanol andwater. The mole fraction of ethanol in the mixtureis 0.90. Also given are the following information :K f of water = 1.86 K kg mol –1 ; K f of ethanol = 2.00K kg mol –1 ; K b of water = 0.52 K kg mol –1 , k b ofethanol = 1.20 K kg mol –1 ; Standard freezing pointof water = 273 K; Standard freezing point ofethanol = 155.7 KStandard boiling point of water = 373 K; Standardboiling point of ethanol = 351.5 KVapour pressure of pure water = 32.8 mm of Hg;vapour pressure of pure ethanol = 40 mm of Hg. Inanswering the following questions, consider thesolutions to be ideal dilute solutions and solute tobe non-volatile, non-electrolytic.15. The freezing point of solution M is(A) 268.7 K (B) 268.5 K(C) 234.2 K (D) 150.9 KXtraEdge for IIT-JEE 50 MAY 2011