MARKING SCHEME CHEMISYRY-2015 (CODE NO. : 56/3/C)

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1 MARKING SCHEME CHEMISYRY-205 (CODE NO. : 56/3/C) Q Value points Mark 2-Methylpropane-,3-diol 2 White phosphorous, because of angular strain in P 4 molecule/ discrete tetrahedral unit. 3 Because carbocation intermediate derived from (CH 3 ) 3 Br is more stable than carbocation from CH 3 CH 2 Br. 4 (i)electrophoresis (ii) by mixing two oppositely charged sols (iii) by boiling (iv) by persistent dialysis (v) by addition of electrolyte (any one) 5 X 4 Y 3 6 (i) pentaamminenitrito-n-cobalt(iii) nitrate (ii) K 2 [Ni(CN) 4 ] 7 (i) CH 3 MgBr, H 3 O + (ii) Cl 2, P 8 It states that solubility of gas in liquid is directly proportional to partial pressure of the gas in equilibrium with the solution. With increase in temperature K H value increases but solubility of gas in liquid decreases. / K H α /solubility 8. It states for solution containing volatile components the partial vapor pressure of each component of the solution is directly proportional to its mole fraction present in the solution. Ideal Solution Non Ideal. It obeys Raoult s Law over It does not obey Raoult s Law. entire range of concentration of solution. 2.Solute Solvent interaction is nearly same as in pure solvent. Solute Solvent interaction is not same as solute-solute or solvent solvent interactions. + (or any other correct difference) 9 Greater number of unpaired electron, greater is the interatomic interactions leading to strong metallic bonding.

2 Zn, no unpaired electrons hence weak metallic bonding., 0 (a) H + (aq) + e- /2H 2 (g) E = 0.00 V is feasible at cathode because its reduction potential is higher than the other reaction. b. Because the overall reaction doesn t involve any ion in the solution whose concentration changes during its lifetime., (i) HBr AgF CH 3 -CH=CH CH 3 -CH 2 -CH 2 -Br CH 3 CH 2 CH 2 F peroxide (ii) PCl 3 /PCl 5 KCN (iii) C 2 H 5 OH C 2 H 5 Cl C 2 H 5 CN (i) CH 3 CH 2 CH=CH 2 (iii) CH 3 NC (ii),, 2 (i) Because NO 2 is an electron withdrawing group (ii) Due to H-Bonding (iii) Reaction occurs by S N mechanism 3 0 -carbocation (CH 3 ) 3 C + is more stable + than CH 3 3 T f = i x K f x m For CaCl 2 i = 3

3 T f = (i x K f x W B X 000)/ (M B x W A ) 2 = 3 x.86 x W B x 000/ X 500 W B = 9.89 g 4 d = Z xm / a 3 x N o 0 g/cm 3 = Z x 8 g/mol /(3 x 0-8 cm) 3 x (6.023 x 0 23 /mol) Z = Nature of cubic unit cell = bcc 5 E cell = E 0 0 R E L = 0.00 (-0.4) E cell = + 0.4V 6 E cell = E o cell V log [ Sn 2+ ] n [ H + ] 2 E cell =E o cell V log [ 0.00] 2 [ 0.0] 2 = V log0 E cell = 0.05 V (i) cis trans (ii) t 2 g 4 / diagram (iii) [NiCl 4 ] 2- -Chloride ion being weak field ligand does not pair d electrons while in [Ni(CO) 4 ], CO being strong field ligand pairs up the d electrons. 7 (i)because physisorption is exothermic process, so it decreases with increase in temperature. (ii)because alum coagulates the impurities present in water. (iii) Due to continuous unbalanced bombardment / zig-zag motion of particles by the molecules of dispersion medium / it allows the particles to settle down. 8 (i) van Arkel method (ii) CO acts as reducing agent (iii) Because S becomes more positive, and G becomes negative.

4 9 (i) Caprolactum (ii) Phenol + Formaldehyde + HCHO (iii),3-butadiene + Acrylonitrile CH 2 =CH-CH=CH 2 + CH 2 =CH-CN (Note: half mark for structure/s and half mark for name/s) 20 (i) Starch (ii) Native Protein found in a biological system with a unique 3-D structure and biological activity is called a native protein. Denatured protein is the protein with no biological activity. (iii) Vitamin-K 2 (i) CH 3 CH(OH) CN (ii) C 6 H 5 COOH (iii)ch 3 CONH 2 22 (a)(i) Because actinoids are radioactive and show wide range of oxidation states. (ii) Transition metals form complex compounds due to - small size, high ionic charge, availability of d orbitals b. 2MnO H+ + 5 SO 2-3 5SO H 2 O + 2 Mn (i) Concern, Compassion, caring, empathy (any two) (ii) By organizing rallies, street play, posters, public speech(any other relevant answer) (iii) Anti depressant drugs are those which inhibit depression E.g. Iproniazide, Phenelzine (or any other) (iv) Saccharine / Sucralose/Alitame/Aspartame(any one) 24 (i) X-X bond in inter halogens is weaker than X-X in halogens (ii) High bond dissociation energy/ due to presence of triple bond. (iii)because bond dissociation enthalpy decreases from NH 3 to BiH 3.,,

5 b. (i) (ii), 24 a) PH 3 P 4 + 3NaOH + 3H 2 O -> 3NaH 2 PO 2 +PH 3 b)helium c) Because bond dissociation energy of F-F bond is lower than that of Cl-Cl. d)4h 3 PO HEAT 3 3H 3 PO 4 + PH 3 e)pbs + 4O 3 PbSO 4 + 4O 2 25 (i) CH 3 CONH 2 + Br 2 + 4KOH CH 3 NH 2 + K 2 CO KBr + 2 H 2 O (ii) C 6 H 5 NH 2 +NaNO 2 + 2HCl K C 6 H 5 N 2 + Cl - + NaCl + 2H 2 O, (iii) b.(i)add CHCl 3 and alc KOH, aniline gives foul smell of isocyanide whereas N- methyaniline does not. (ii)when (CH 3 ) 2 NH reacts with Benzene Sulphonyl Chloride(Hinsberg Reagent) gives ppt which is insoluble in alkali whereas (CH 3 ) 3 N does not reacts with Hinsberg s Reagent. (Or any other correct distinguishing test)

6 25 a. (i) (ii) (iii),, 26 b. (i) (CH 3 ) 3 N < C 2 H 5 NH2 < C 2 H 5 OH (ii) p-nitoaniline < aniline < p-methylaniline a. Rate of reaction is defined as change in concentration of reactants or products per unit time. Factors: concentration of reactant, temperature, pressure, surface area (any two) b. log(k 2 /k ) = Ea/2.303R [/T /T 2 ], 26 log (8 x 0-2 / 4x 0-2 ) = E a /2.303 x 8.34 [/300 /30] log2 = Ea/2.303 x 8.34 [/300 /30] Ea = J/mol or 53.6 kj/mol (a)(i) Rate becomes 4 times (ii) 2 nd order b)t /2 = k 23. min =0.693 k k = 0.03 min - k = log [ A 0 ] t [A] t = log

7 t = x min 0.03 t = min