Prerna Tower, Road No 2, Contractors Area, Bistupur, Jamshedpur , Tel (0657) , PART B CHEMISTRY

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1 R Prerna Tower, Road No, ontractors Area, Bistupur, Jamshedpur , Tel (0657)189, JEE MAIN April 013 PART B HEMISTRY 31. Which of the following complex species is not expected to exhibit optical isomerism? (1) [o (en) 3 ] 3 () [o (en) ] (3) [o (NH 3 ) 3 3 ] (4) [o (en) (NH 3 ) ] 31. (3) NH3 NH 3 H3N (Meridional) (inactive) H3N NH3 H3N (facial) (inactive) Both have plane of symmetry. 3. Which one of the following molecules is expected to exhibit diamagnetic behaviour? (1) () N (3) (4) S 3. (1), () σ 1s σ* 1s σ s σ* s π px π py diamagnetic N σ 1s σ* 1s σ s σ* s π px π py π py σ pz diamagnetic If s, p mixing is not considered then N is most appropriate. 33. A solution of ( ) 1 chloro 1 phenylethane in toluene racemises slowly in the presence of a small amount of Sb 5, due to the formation of : (1) carbanion () carbene (3) carbocation (4) free radical 33. (3) Ph Ph H H 3 Sb 5 H H 3 Stable carbocation Sb 5 is lewis acid JEE MAIN 013 (07 Apr 13) Question & Solutions 1 www. prernaclasses.com

2 34. Given E 0 r 3 / r = 0.74 V; E 0 Mn 4 / Mn = 1.51 V ; E 0 r 7 / r 3 = 1.33 V ; E 0 / r = 1.36 V Based on the data given above, strongest oxidising agent will be : (1) () r 3 (3) Mn (4) Mn (4) Greater positive reduction potential, greater will be the reduction, hence stronger oxidising agent. 35. A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 ml to 375 ml at a constant temperature of As it does so, it absorbs 08 J of heat. The values of q and w for the process will be : (R = J/ mol K) (ln 7.5 =.01) (1) q = 08 J, w = 08 J () q = 08 J, w = 08 J (3) q = 08 J, w = 08 J (4) q = 08 J, w = 08 J 35. (1) q = 08 J U = 0 U = q w w = 08 J 36. The molarity of a solution obtained by mixing 750 ml of 0.5 (M) H with 50 ml of (M) H will be : (1) M () 1.00 M (3) 1.75 M (4) M 36. (1) M H = ( ) / (750 50) = M 37. Arrange the following compounds in order of decreasing acidity : I ; H3 II ; N III ; 3 IV (1) II > IV > I > III () I > II > III > IV (3) III > I > II > IV (4) IV > III > I > II 37. (3) Greater the I and R power greater acidic strength I & R (1 / acidic strength) So III > I > II > IV 38. For gaseous state, if most probable speed is denoted by *, average speed by and mean square speed by, then for a large number of molecules the ratios of these speeds are : (1) * : : = 1.5 : 1.18 : 1 () * : : = 1.18 : 1.5 : 1 (3) * : : = 1 : 1.18 : 1.5 (4) * : : = 1 : 1.5 : (3) * : : = RT 8 RT 3 RT : : M π M M = 1 : 1.18 : 1.5 JEE MAIN 013 (07 Apr 13) Question & Solutions www. prernaclasses.com

3 39. The rate of a reaction doubles when its temperature changes from 300 K to 310 K. Activation energy of such a reaction will be : (R = JK 1 mol 1 and log = 0.301) (1) 53.6 kj mol 1 () 48.6 kj mol 1 (3) 58.5 kj mol 1 (4) 60.5 kj mol 1 Ea (1) log = Ea = kj 40. A compound with molecular mass 180 is acylated with H 3 to get a compound with molecular mass 390. The number of amino groups present per molecule of the former compound is : (1) () 5 (3) 4 (4) 6 40 () R H3 NH R NH H3 for a single NH group the increase in mass is 4 So number of amino group = ( ) / 4 = Which of the following arrangements does not represent the correct order of the property stated against it? (1) V < r < Mn < Fe : paramagnetic behaviour () Ni < o < Fe < Mn : ionic size (3) o 3 < Fe 3 < r 3 < Sc 3 : stability in aqueous solution (4) Sc <Ti < r < Mn : number of oxidation states 41. (1) Number of unpaired e of Mn = 5 Number of unpaired of Fe = 4 So paramagnetic behaviour of Fe < Mn. 4. The order of stability of the following carbocations : H H = H H ; I H3 H H ; II III is : (1) III > II > I () II > III > I (3) I > II > III (4) III > I > II 4. (4) Greater the resonating structure, greater will be the stability. JEE MAIN 013 (07 Apr 13) Question & Solutions 3 www. prernaclasses.com

4 43. onsider the following reaction x Mn 4 y 4 z H x Mn y (z / ) H The values of x, y and z in the reaction are respectively : (1) 5, and 16 (), 5 and 8 (3), 5 and 16 (4) 5, and (3) 7 3 5e xmn4 y4 zh xmn y (z/)h e Mn H Mn 5 (16 / ) H 44. Which of the following is the wrong statement? (1) N and N are not isoelectronic. () 3 molecule is bent. (3) zone is violet black in solid state. (4) zone is diamagnetic gas. 44. (1) Both N & N are valence isoelectronic. ther statements are correct. 45. A gaseous hydrocarbon gives upon combustion 0.7 g. of water and 3.08 g. of. The empirical formula of the hydrocarbon is : (1) H 4 () 3 H 4 (3) 6 H 5 (4) 7 H (4) x H y x (y/)h 1 mol x mol (y/) mol x = (3.08 / 44) = 0.07 (y / ) = (0.7 / 18) y = 0.08 So Emprical formula is x H y = 0.07 H 0.08 = 7 H In which of the following pairs of molecules/ions, both the species are not likely to exist? (1) H, He () H, He (3) H, He (4) H, He 46. (3) H and He both have zero bond order. 47. Which of the following exist as covalent crystals in the solid state? (1) Iodine () Silicon (3) Sulphur (4) Phosphorus 47. () Silicon exists as covalent crystal rest all are molecular solid. 48. Synthesis of each molecule of glucose in photosynthesis involves : (1) 18 molecules of ATP () 10 molecules of ATP (3) 8 molecules of ATP (4) 6 molecules of ATP 48. (1) For complete synthesis of one molecule of glucose requires 18 ATPs and 1 NADPH. 4 JEE MAIN 013 (07 Apr 13) Question & Solutions 4 www. prernaclasses.com

5 49. The coagulating power of electrolytes having ions Na, Al 3 and Ba for arsenic sulphide sol increases in the order : (1) Al 3 < Ba < Na () Na < Ba < Al 3 (3) Ba < Na < Al 3 (4) Al 3 < Na < Ba 49. () Greater the valency, greater is the power to cause precipitation. 50. Which of the following represents the correct order of increasing first ionization enthalpy for a, Ba, S, Se and Ar? (1) a < S < Ba < Se < Ar () S < Se < a < Ba < Ar (3) Ba < a < Se < S < Ar (4) a < Ba < S < Se < Ar 50. (3) Ionisation energy increases across the period and decreases down the group. Z 51. Energy of an electron is given by E = J. Wavelength of light required to n excite an electron in an hydrogen atom from level n = 1 to n = will be : (h = Js and c = ms 1 ) (1) m () m (3) m (4) m 51. (1) (hc / λ) = (1 / n 1 1 / n ) λ = m. 5. ompound (A), 8 H 9 Br, gives a whtie precipitate when warmed with alcoholic AgN 3. xidation of (A) given an acid (B), 8 H 6 4, (B) easily forms anhydride on heating. Identify the compound (A). (1) HBr () H5 Br (3) HBr (4) H Br H 3 H3 H3 5. (4) HBr H3 3 AgN H AgBr H3 HBr H3 [ ] KMn 4 JEE MAIN 013 (07 Apr 13) Question & Solutions 5 www. prernaclasses.com

6 53. Four successive members of the first row transition elements are listed below with atomic numbers which one of them is expected to have the highest E 0 M 3 /M value? (1) r(z = 4) () Mn(Z = 5) (3) Fe(Z = 6) (4) o(z = 7) 53. (4) It is fact. 54. How many litres of water must be added to 1 litre of an aqueous solution of H with a ph of 1 to create an aqueous solution with ph of? (1) 0.1 L () 0.9 L (3).0 L (4) 9.0 L 54. (4) ph = 1 ph = [H ] = 0.1 [H ] = = V 0.01 V = 10 Lit So Volume of water added = 10 1 = 9 Lit 55. The first ionisation potential of Na is 5.1 ev. The value of electron gain enthalpy of Na will be : (1).55 ev () 5.1 ev (3) 10. ev (4).55 ev 5. 1 ev 55. () Na Na e Na e Na E.A = 5.1 ev 56. An organic compound A upon reacting with NH 3 gives B. n heating, B gives. in presence of K reacts with Br to give H 3 H NH. A is : (1) H 3 () H 3 H H (3) H 3 H (4) H 3 H H 3 NH (4) H 3 H H 3 H NH K H 3 H NH H Br 3 H NH Stability of the species Li, Li and Li increases in the order of : (1) Li < Li < Li () Li < Li < Li (3) Li < Li < Li (4) Li < Li < Li 57. () Greater the bond order, greater is the stability So Li is more stable Between Li and Li, Li has greater antibonding e 58. An unknown alcohol is treated with the Lucas reagent to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism : (1) Secondary alcohol by S N 1 () Tertiary alcohol by S N 1 (3) Secondary alcohol by S N (4) Tertiary alcohol by S N 58. () Tertiary carbocation is more stable. So tertiary alcohol proceeds through S N 1 mechanism. JEE MAIN 013 (07 Apr 13) Question & Solutions 6 www. prernaclasses.com

7 59. The gas leaked from a storage tank of the Union arbide plant in Bhopal gas tragedy was : (1) Methylisocyanate () Methylamine (3) Ammonia (4) Phosgene 59. (1) It is fact 60. Experimentally it was found that a metal oxide has formula M Metal M, is present as M and M 3 in its oxide. Fraction of the metal which exists as M 3 would be : (1) 7.01% () 4.08% (3) 6.05% (4) 5.08% 60. () 3M M 3 x (x / 3) So cation vaccancy = x (x / 3) = (x / 3) (x / 3) = = 0.0 x = 0.06 So % M 3 = ( 0.06 / 3) 100 = 4% JEE MAIN 013 (07 Apr 13) Question & Solutions 7 www. prernaclasses.com

( ) PART A CHEMISTRY. Li 6 1s 1s 2s. Li 7 1s 1s 2s 2s 4 3. Li + 2 is more stable than Li 2 because Li 2 has more numbers of antibonding electrons.

( ) PART A CHEMISTRY. Li 6 1s 1s 2s. Li 7 1s 1s 2s 2s 4 3. Li + 2 is more stable than Li 2 because Li 2 has more numbers of antibonding electrons. JEE (MAIN)-13-CMP - PART A CHEMISTRY 1. An unknown alcohol is treated with the Lucas reagent to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what