CHEMISTRY MARKING SCHEME FOREIGN-2016 SET -56/2/1/F

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1 CHEMISTRY MARKING SCHEME FOREIGN-206 SET -56/2//F Q.no. Answers Marks Like Charged particles cause repulsion/ Brownian motion/ solvation 2 Because of some crystallization. 3 Reaction (ii) 4 NO 2 gas 5 N,N-dimethylbutanamide 6 i) [Co(NH 3 ) 4 Cl 2 ]Cl ii) Tetraamminedichloridocobalt(III) chloride 7 7 OR

2 8 Henry s law states that the mole fraction of gas in the solution is proportional to the partial pressure of the gas over the solution. Applications: solubility of CO 2 gas in soft drinks /solubility of air diluted with helium in blood used by sea divers or any other Solubility of gas in liquid decreases with increase in temperature. 9 0 X = CH 3 -CO-CH 2 -CH 3 / Butan-2-one Y= CH 3 -CH(OH)-CH 2 -CH 3 / Butan-2-ol i) ii) + k = log t p i 2p i -p t = log x = log = x = atm - or atm - (approx.) 2

3 2 i)because of the resonance stabilization of the conjugate base i.e enolate anion or diagrammatic representation. iii)because the carboxyl group gets bonded to the catalyst anhyd.alcl 3 (lewis acid). ( note: part ii is deleted because of printing error and mark alloted in part i and part iii ) OR 2 i)c 6 H 5 CH 3 CrO 3 /(CH 3 CO) 2 O C 6 H 5 CH(OCOCH 3 ) 2 H 2 O C 6 H 5 CHO ii)ch 3 COOH Cl 2 /P Cl-CH 2 -COOH iii)ch 3 COCH 3 Zn(Hg)/conc.HCl CH 3 CH 2 CH 3 x3=3 ( Or by any other correct method) 3 d = z x M N A x a 3 Or d = z x w N x a 3 Where w is weight and N is no. of atoms. d = 4 x 200 g 2.5 x0 24 x ( 400 x 0-0 cm) 3 d = 5 g cm -3 (or by any other correct method) 4 i) It is a process in which both adsorption and absorption can take place simultaneously. ii) It is the potential difference between the fixed layer and the diffused/ double layer of opposite charges around the colloidal particles. iii) It is the temperature above which the formation of micelles takes place. 3

4 5 T f = ik f m For complete ionisation of Na 2 SO 4 i=3 T f = T 0 f - T f = 3 x.86 K kg mol - x 2g x 000 g kg - 42g mol - 50 g T f =.57 So, T f = -.57 o C or 27.43K 6 i)because of higher oxidation state ( +5) / high charge to size ratio / high polarizing power. ii)because of high interelectronic repulsion. iii)because of its low bond dissociation enthalpy and high hydration enthalpy of F -. x3=3 7 i)a : C 6 H 5 CONH 2 B : C 6 H 5 NH 2 C : C 6 H 5 NHCOCH 3 ii)a: C 6 H 5 NO 2 B : C 6 H 5 NH 2 C: C 6 H 5 - NC 8 (i) Butadiene and acrylonitrile CH 2 = CH CH = CH 2 and CH 2 =CH-CN + (ii) Vinyl chloride CH 2 =CH-Cl + (iii) Chloroprene Cl + CH 2 = C CH = CH 2 9 i) ii) iii) Peptide linkage / -CO-NH- linkage Water soluble-vitamin B / C Fat soluble- Vitamin A /D /E /K + 4

5 20 i) dsp 3, Diamagnetic, low spin + ii) The energy used to split degenerate d-orbitals due to the presence of ligands in a definite geometry is called crystal field splitting energy. 2 i)iodine is heated with Zr or Ti to form a volatile compound which on further heating decompose to give pure Zr or Ti. or Zr(impure) + 2I 2 ZrI 4 (volatile) 22 ZrI 4 800K Zr(pure) + 2I 2 ii)cryolite lowers the m.p.of alumina mix / acts as a solvent / brings conductivity. (iii) Role of NaCN in the extraction of Ag is to do the leaching of silver ore in the presence of air. or 4Ag(s) + 8CN - (aq) + 2H 2 O + O 2 (g) 4[Ag(CN) 2 ] - + 4OH - i) CH 2 Cl HO ii) Br CH 3 x 3=3 iii) CH 3 CH 2 ONO 5

6 23 (i)caring,dutiful, Concerned, compassionate ( or any other two values) ii)because higher doses may have harmful effects and act as poison which cause even death. iii)tranquilizers are a class of chemical compounds used for treatment of stress or even mental diseases. ex. chlordiazepoxide, equanil,veronal, serotonin,valium (or any other two examples) a) Given E o Cell = V ; F = 96500C mol - n = 6 (from the given reaction) rg O = n x F x E o Cell rg O = 6 x C mol - x 0.30V = - 73,700 J / mol or kj / mol log Kc = n E o Cell log Kc = 6 x log Kc = 30.5 b)a Because E o value of A shows that on coating,a acts as anode and Fe acts as a cathode and hence A oxidises in prefence to Fe and prevent corrosion / or E o cell is positive and hence A oxidises itself to prevent corrosion of Fe/E o value is more negative. ( or any other correct reason) OR 6

7 24 a) ᴧ m = κ c = x 0-5 S cm - x 000cm mol L - L ᴧ m = Scm 2 mol - ᴧ o = λ o (H + ) + λ o (CH 3 COO - ) = ( ) Scm 2 mol - ᴧ o = Scm 2 mol - α = ᴧ m ᴧ o = Scm 2 mol Scm 2 mol - α = 0. b)secondary battery or rechargeable battery Pb(s) + PbO 2 (s) + 2SO 4 2 (aq) + 4H + (aq) 2PbSO 4 (s) + 2H 2 O(l) 25 a) i)because of higher oxidation state (+7) of Mn. ii)because it has one unpaired electron in 3d orbital in its +2 oxidation state / or it has incompletely filled d-orbital in +2 oxidation state. iii)because of comparable energies of 5f, 6d and 7s orbitals. b) 2MnO 2 + 4KOH + O 2 2K 2 MnO 4 + 2H 2 O 3MnO H + 2MnO 4 - OR + MnO 2 + 2H 2 O + 7

8 25 a) i)cr, because of maximum no. of unpaired electrons cause strong metallic bonding. ii)mn, because it attains stable half -filled 3d 5 configuration in +2 oxidation state. iii)zn, because of no unpaired electron in d-orbital. b) Na 2 Cr 2 O KCl K 2 Cr 2 O NaCl + 26 a) i) (CH 3 ) 3 C-I + CH 3 -OH i) CH 3 -CH 2 -C-CH 3 ii) O b).i) ii). OR 8

9 26 a). (i) OH Br 2 (aq) Br OH Br O Br pyridine (ii) CH 3 CH 2 OH + CH 3 COCl CH 3 CH 2 O-COCH 3 + HCl (iii). OCH 3 OH O HI + CH 3 -I (b)(i) Warm each compound with iodine and sodium hydroxide. Phenol : No yellow ppt formed Ethanol: Yellow ppt of Iodoform are formed. ii)on adding lucas reagent ( HCl/anhyd.ZnCl 2 ), Propan-2-ol gives white turbidity after 5 minutes whereas 2-methylpropan-2-ol gives white turbidity immediately. (or any other suitable test) Name Signature Name Signature Dr. (Mrs.) Sangeeta Bhatia Sh. S.K. Munjal Dr. K.N. Uppadhya Prof. R.D. Shukla Dr. (Mrs.) Sunita Ramrakhiani Sh. S. Vallabhan, Principal Mr. K.M. Abdul Raheem Mrs. Sushma Sachdeva Ms. Seema Bhatnagar Sh. Pawan Singh Meena Sh. D.A. Mishra Sh. Rakesh Dhawan Ms. Nirmala Venkateswaran Mrs. Deepika Arora Ms. Minakshi Gupta Sh. Mukesh Kaushik Mr. Roop Narayan Ms. Garima Bhutani Sh. Praveen Kumar Agrawal 9

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