CHEMISTRY (043)
Marking Scheme
SECTION A
1.(d)N-N is weaker than P-P
other statements as incorrect as Phosphorus has a higher melting point due to bigger size than
Nitrogen. Nitrogen is inert due to formation of triple bonds and has a lower covalence due to
non - availability of d –orbitals
2. (c)metal deficiency defect (anion is missing from lattice site)
In Frenkel defect the smaller ion occupies the interstitial sites and Schottky defect equal number
of cations and anions are missing. Interstitial defect an atom or molecule occupies intestinal sites
so in these three defects the ratio of positive and negative ions (Stoichiometric) of a solid is not
disturbed in these three
3. (b) Raoult’s law
4. (c) Metal excess defect (formation of F centres)
5. (c) 1,4-dicholorbenzene ( para isomers are more symmetric and ortho and meta )
6. (d) existence of alpha and beta forms of glucose .
7. (c) SN2 reaction (alkoxide ion reacts with primary alkyl halide in a single step to form ether)
8. (b) a mixture of HOCl and HCl is produced in the presence of sunlight
Cl2(g) +H2O (l) HCl (g) +HOCl(aq)
9. (a)protonation of alcohol molecule
10. Amorphous solids are:
(a) isotropic (the value of any physical property is same along any direction)
11. (c) Reimer- Tiemann reaction ( Kolbe’s reaction is used to prepare salicylic acid, Etard
reaction for benzaldehyde, Reimer- Tiemann reaction for salicylaldehyde and Stephen’s
reduction for aldehyde)
12. (d)22 carat gold (it is an alloy so solid in solid solution)
13. (a) Hydrogen bonding (alcohols form intermolecular hydrogen bonds)
14. (b)H2S (boiling point increases down the group but water forms strong hydrogen bonds so
has higher boiling point than H2S)
15. (d)pH does not affect the primary structure of protein (pH effects the tertiary structure)
16. (b) 1 –Phenyl -3- bromopropane
((C6H5)CH2CH=CH2 + HBr (organic peroxide) (C6H5)CH2CH2CH2Br anti-Markovnikov
addition)
17. (b) It gives nitroethane on heating with aqueous solution of AgNO2
(C2H5Br reacts with metallic Na to give butane , gives ethene on boiling with alcoholic potash.
and forms C2H5SH (thiol) on heating with alcoholic KSH)
18. (c)4 (Covalency of nitrogen is restricted to 4 due to non availability of d orbitals)
19. (b)exothermic and reversible process (according to Le -Chatlier principle Solubility of gases
in liquids decreases with rise in temperature)
20. (a)Nitrogen (due to small size and high electronegativity N-N is weak)
21.(c)glycogen (It is a polymer of glucose)
22. (d) Helium (He is monoatomic and has low atomic mass)
23.(c) miscible in water in all proportions Lower molecular mass alcohols are able to form
hydrogen bonds with water
24.(d)+7 (Cl : 1s2
2s2
2p6
3s2
3p5
)
25.(a)When placed in water containing more than 0.9% (mass/ volume) NaCl solution because
fluid inside blood cells is isotonic with 0.9% NaCl solution
SECTION B
26. (a) 7.5 mol
ΔTf = Kf m
ΔTf = Kf n2 x 1000
w1
14 = 1.86 x n2 x 1000
1000
n2 = 7.5 mol
27. (b) CH3Cl, Na, Dry ether
28. (d) XeO2F2 + 4HF
XeF4 + H2O XeO2F2 + 4HF
29. (c) It undergoes inversion in the configuration on hydrolysis
30. (b) partial double bond character of C-OH bond
31. (a)Nitrogen (High IE of N is because of smallest size in the group and completely half - filled
p subshell)
32. (d) M2O3
Metal M ions form ccp structure. Let number of ions of M be : X
No. of tetrahedral voids = 2x
No. of octahedral voids = x
Number of oxide ions will be 1/2 x + ½ (2x) = 3/2 x
Formula of oxide = MxO3/2 x = M2O3
33. c) X = o and p–chlorotoluene Y = trichloromethylbenzene
The reaction of toluene with Cl2 in presence of FeCl3 gives ‘X’ due to electrophilic substitution
reaction taking place at ortho and para positions and reaction in the presence of light gives ‘Y’,
due to substitution reaction occurring via free radical mechanism
. Thus ‘X’ and ‘Y’are X = o and p–chlorotoluene Y = trichloromethylbenzene
34. (d)angular, 128pm ; 128pm (Ozone is a resonance hybrid of two equivalent structures)
35. (c) Osmosis
36. d) A= OHC-(CHOCOCH3)4-CH2OCOCH3 B= COOH-(CH2)4 -COOH
37. (d) Adsorption of litmus by Al(OH)3
In lake test for Al3+ ions, there is the formation of coloured ‘floating lake’ In lake test for Al3+
ions, there is the formation of coloured ‘floating lake’ due to adsorption
38. (c) 3 g/cm3
Using formula
Density = ( Z X m )
(a3 X Na )
D = . 4 x 58.5 .
(0.5x10-7)
3
x 6.023x1023
= 3.1 g/cm3
39. (d) BiH3<SbH3<AsH3<PH3<NH3 [ increasing bond angle ] correct order
(a) I2 < Br2<F2<Cl2 [ increasing bond dissociation enthalpy]: incorrect order , correct
order is Cl2 > Br2 > F2 > I2.
(b) H2O > H2S<H2Te<H2Se [ increasing acidic strength]: incorrect order , correct
order is
H2O<H2S<H2Se<H2Te
(c) NH3 < N2O< NH2OH<N2O5 [ increasing oxidation state ] : incorrect order NH3
(Oxidation state -3) N2O (Oxidation state +1) NH2OH(Oxidation state -1) N2O5
(Oxidation state +5)
40. (d) 2- methylpropanal and isopropyl magnesium iodide
41. (b) 2- chloromethylphenol
42. (a)Ammonia is the weakest reducing agent and the strongest base among Group 15 hydrides.
The reducing character of hydrides increases down the group due to decrease in bond
dissociation enthalpy.
43 (a)(i) and (iv)
(i)CH3CH2CH(OH)CH3 (secondary) (ii) (C2H5)3COH (tertiary)
(iii) (iv)
Phenol not an alcohol secondary
44. (d)vicinal dibromide
CH2=CH2 + Br2 → BrCH2 - CH2Br
45. (c)
Assertion: Electron gain enthalpy of oxygen is less than that of Flourine but greater than
Nitrogen. (correct)
Reason: Ionisation enthalpies of the elements follow the order Nitrogen > Oxygen > Fluorine
(incorrect)
Ionisation enthalpies of the elements follow the order Fluorine >Nitrogen > Oxygen
46. (b) Assertion: Alkyl halides are insoluble in water. (correct)
Reason: Alkyl halides have halogen attached to sp3
hybrid carbon. (correct)
Alkyl halides are insoluble in water because they are unable to form hydrogen bonds with water
or break pre-existing hydrogen bonds.
47. ( c)Assertion: Molarity of a solution changes with temperature. (correct)
Reason: Molarity is a colligative property. (incorrect)
Molarity is a means to express concentration. It is not a physical property.
48. (a) Assertion: SO2 is reducing while TeO2 is an oxidising agent. (correct)
Reason: Reducing property of dioxide decreases from SO2 to TeO2 (correct and reason for
Assertion)
49. (c ) Assertion: Cryoscopic constant depends on nature of solvent. (correct)
Reason: Cryoscopic constant is a universal constant (incorrect)
Cryoscopic constant various with type of solvent
SECTION C
50. (b) i-D, ii-C, iii- A, iv-B
Amino acids form proteins and exist as zwitter ion , Thymine is a nitrogenous base in DNA,
Insulin is a protein , phosphodiester linkage is found in nucleic acids so also in DNA and Uracil
is nitrogenous base found in RNA which is a nucleic acid.
51. (d)Helium: meteorological observations :: Argon: metallurgical processes
Nitrogen: 1s2
2s2
2p3 :: Argon:1s2
2s2
2p6
is configuration of Neon not Argon
Carbon: maximum compounds :: Xenon: no compounds , Xenon forms compounds
XeF2: Linear :: ClF3: Trigonal planar , ClF3 is T shaped not trigonal planar
52. (a) A : Isomers B: Enantiomer
Isomers have Same molecular formula but different structure
Enantiomers are Non superimposable mirror images
Q53. (c)6
The radius of Ag+ ion is 126pm and of I- ion is 216pm. The coordination number of Ag+ ion is:
ρ = rcation/ranion = 126/ 216 = 0.58
Radius ratio lies in the range 0.414 – 0.732, so has coordination number 6 or 4 according to the
table.
Since none of the options is 4, so the answer is 6
Q54. (d)290 pm
Square planar means ratio ratio is between 0.414 – 0.732
If radius of cation is 120 pm then anion should be in the range ρ = rcation/ranion
0.414 = 120/ x so x = 289.8 = 290 pm
0.732 = 120/ x so x = 163.9 = 164 pm
Q55. (a)all of its nearest neighbour anions
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