NEET 2020 Paper

Date : 13th September 2020

Time : 02 : 00 pm - 5 : 00 pm
Subject : Chemistry

46. Identify compound X in the following sequences of reactions :

(1) (2) (3) (4)

Sol. 1

47. Identify a molecule which does not exist.

(1) C2 (2) O2 (3) He2 (4) Li2
Sol. 3
Diatomic molecule for which bond order is zero or negative does not exist.
Molecule BO
C2 2
O2 2
He2 Zero
Li2 1

48. Which of the following is a natural polymer ?

(1) polybutadiene (2) poly (Butadiene-acrylonitrile)
(3) cis-1,4-polyisoprene (4) poly (Butadiene-styrene)
Sol. 3

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49. An increase in the concentration of the reactants of a reaction leads to change in :

(1) threshold energy (2) collision frequency
(3) activation energy (4) heat of reaction
Sol. 2
Collision frequency, as number of molecules per unit volume increases.

50. Anisole on cleavage with HI gives :

(1) (2)

(3) (4)

Sol. 3

175
51. The number of protons, neutrons and electrons in 71 Lu
, respectively, are :
(1) 71, 71 and 104 (2) 175, 104 and 71
(3) 71, 104 and 71 (4) 104, 71 and 71
Sol. 3
np175
p71
Lu

 no. of protons = 71
no. of neutrons = 175 – 71 = 104
no. of electrons = 71

52. The calculated spin only magnetic moment of Cr2+ ion is :

(1) 5.92 BM (2) 2.84 BM
(3) 3.87 BM (4) 4.90 BM
Sol. 4
Cr2+  1s2 2s2 2p6 3s2 3p6 3d4
 n (number of unpaired electrons) = 4

  = n n  2

= 4 4  2
= 4.8989
= 4.9 B.M.
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53. Match the following :

Oxide Nature
(a) CO (i) Basic
(b) BaO (ii) Neutral
(c) Al2O3 (iii) Acidic
(d) Cl2O7 (iv) Amphoteric
Which of the following is correct option ?
(a) (b) (c) (d)
(1) (iii) (iv) (i) (ii)
(2) (iv) (iii) (ii) (i)
(3) (i) (ii) (iii) (iv)
(4) (ii) (i) (iv) (iii)
Sol. 4
CO Neutral
BaO Basic
Al2O3 Amphoteric
Cl2O7 Acidic

54. Urea reacts with water to form A which will decompose to form B. B when passed
through Cu2+ (aq), deep blue colour solution C is formed. What is the formula of C from
the following ?
(1) Cu(OH)2 (2) CuCO3.Cu(OH)2
(3) CuSO4 (4) [Cu(NH3)4]2+
Sol. 4

55. Match the following and identify the correct option.

(a) CO(g) + H2(g) (i) Mg(HCO3)2 + Ca(HCO3)2
(b) Temporary hardness of water (ii) An electron deficient hydride
(c) B2H6 (iii) Synthesis gas
(d) H2O2 (iv) Non-planar structure
(a) (b) (c) (d)
(1) (iii) (iv) (ii) (i)
(2) (i) (iii) (ii) (iv)
(3) (iii) (i) (ii) (iv)
(4) (iii) (ii) (i) (iv)

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Sol. 3
 CO(g) + H2(g) = Water gas or synthesis gas
 Temporary hardness of water is due to bicarbonates of Ca2+ & Mg2+
 B2H6 is a electron deficient compound due to presence of banana bond.
 H2O2 open book like structure which is non-planar

56. The mixture which shows positive deviation from Raoult’s law is :
(1) Acetone + Chloroform (2) Chloroethane + Bromoethane
(3) Ethanol + Acetone (4) Benzene + Toluene
Sol. 3
Acetone + ethanol shows positive deviation from Raoult’s law. Pure ethanol possesses
H-bonding and adding acetone to ethanol causes breaking of some H-bonds.
This causes increase in observed vapour pressure.

57. The freezing point depression constant (Kf) of benzene is 5.12 K kg mol–1. The freezing
point depression for the solution of molality 0.078 m containing a non-electrolyte sol-
ute in benzene is (rounded off upto two decimal places) :
(1) 0.40 K (2) 0.60 K (3) 0.20 K (4) 0.80 K
Sol. 1
Tf = ikfm
 Tf = 1 × 5.12 × 0.078
Tf = 0.3993
Tf = 0.40 K

58. Which of the following set of molecules will have zero dipole moment ?
(1) Nitrogen trifluoride, beryllium difluoride, water, 1,3-dichlorobenzene
(2) Boron trifluoride, beryllium difluoride, carbon dioxide, 1,4-dichlorobenzene
(3) Ammonia, beryllium difluoride, water 1,4-dichlorobenzene
(4) Boron trifluoride, hydrogen fluoride, carbon dioxide, 1,3-dichlorobenzene
Sol. 2

=0 Non-polar molecule

=0 Non-polar molecule

=0 Non-polar molecule

=0 Non-polar molecule

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59. A tertiary butyl carbocation is more stable than a secondary butyl carbocation because
of which of the following ?
(1) –R effect of –CH3 groups (2) Hyperconjugation
(3) –I effect of –CH3 groups (4) + R effect of –CH3 groups
Sol. 2

60. Find out the solubility of Ni(OH)2 in 0.1 M NaOH. Given that the ionic product of Ni(OH)2
is 2×10–15.
(1) 1 × 10–13 M (2) 1 × 108 M
(3) 2 × 10–13 M (4) 2 × 10–8 M
Sol. 3
Ni(OH)2 Ni2+ + 2OH–
– s 0.1 M
 Ksp = [Ni ] [OH ]
2+ – 2

 ksp = s × (0.1)2

2  1015
 s=
0.12
 s = 2 × 10–13 M

61. Reaction between acetone and methylmagnesium chloride followed by hydrolysis will
give:
(1) Tert. butyl alcohol (2) Isobutyl alcohol
(3) Isopropyl alcohol (4) Sec. butyl alcohol
Sol. 1

62. Which of the following amine will give the carbylamine test?

N(CH3)2 NHC2H5 NH2 NHCH 3

(1) (2) (3) (4)

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Sol. 3

Carbylamine reaction is give by 1° amine & aniline.

63. An alkene on ozonolysis gives methanal as one of the product. Its structure is:

CH2–CH=CH2 CH2CH 2CH 3 CH=CH–CH 3 CH2–CH 2–CH 3

(1) (2) (3) (4)

Sol. 1

64. A mixture of N2 and Ar gases in a cylinder contains 7 g of N2 and 8 g of Ar. If the total
pressure of the mixture of the gases in the cylinder is 27 bar, the partial pressure of N2
is:
[Use atomic masses (in g mol–1): N = 14, Ar = 40]
(1) 15 bar (2) 18 bar (3) 9 bar (4) 12 bar
Sol. 1
According to Dalton’s law
PN2  N2 Ptotal

 7 
 28 
   27
PN =  8 7 
2
  
 40 28 
 0.25 
PN2 = 
0.2  0.25   27
 
PN = 15 bar
2

65. Which of the following is the correct order of increasing field strength of ligands to form
coordination compounds ?
(1) F– < SCN– < C2O2–
4
< CN– (2) CN– < C2O2–
4
< SCN– < F–

(3) SCN– < F– < C2O2–

4
< CN– (4) SCN– < F– < CN– < C2O2–
4

Sol. 3
Fact from spectrochemical series.

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66. Paper chromatography is an example of :

(1) Thin layer chromatography (2) Column chromatography
(3) Adsorption chromatography (4) Partition chromatography
Sol. 4
It is an example of partition chromatography as mixture of substance are separated by
partition.

67. Sucrose on hydrolysis gives:

(1) -D-Glucose + -D-Fructose (2) -D-Fructose + -D-Fructose
(3) -D-Glucose + -D-Fructose (4) -D-Glucose + -D-Glucose
Sol. 1

68. The rate constant for a first order reaction is 4.606 × 10–3 s–1. The time required to
reduce 2.0 g of the reactant to 0.2 g is:
(1) 500 s (2) 1000 s (3) 100 s (4) 200 s
Sol. 1

1 Co
t = K ln C
t

1 2
=  2.303 log
4.606  103 0.2
1
= log10
2  103
= 500 sec

69. Reaction between benzaldehyde and acetophenone in presence of dilute NaOH is known
as:
(1) Cross Cannizzaro’s reaction (2) Cross Aldol condensation
(3) Aldol condensation (4) Cannizzaro’s reaction
Sol. 2

Two different carbonyl compound is treated with base known as cross-aldol condensation.

70. Which of the following is not correct about carbon monoxide?

(1) The carboxyhaemoglobin (haemoglobin bound to CO) is less stable than
oxyhaemoglobin.
(2) It is produced due to incomplete combustion.
(3) It forms carboxyhaemoglobin.
(4) It reduces oxygen carrying ability of blood.

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Sol. 1
CO when combine with haemoglobin it forms carboxyhaemoglobin which more stable
than oxyhaemoglobin thats why it reduces oxygen carring ability of blood.

71. Hydrolysis of sucrose is given by the following reaction.

Sucrose + H2O Glucose + Fructose
If the equilibrium constant (Kc) is 2 × 1013 at 300 K, the value of rGº at the same
temperature will be:
(1) 8.314 J mol–1 K–1 × 300 K × ln(3 × 1013)
(2) –8.314 J mol–1 K–1 × 300 K × ln(4 × 1013)
(3) –8.314 J mol–1 K–1 × 300 K × ln(2 × 1013)
(4) 8.314 J mol–1 K–1 × 300 K × ln(2 × 1013)
Sol. 3
G°= –RT ln K
 G° = – 8.314 J mol–1 K–1 × 300 K × ln (2 × 1013)

72. HCl was passed through a solution of CaCl2, MgCl2 and NaCl. Which of the following
compound(s) crystallise(s)?
(1) only MgCl2 (2) NaCl, MgCl2 and CaCl2
(3) Both MgCl2 and CaCl2 (4) Only NaCl
Sol. 1
MgCl2 has least solubility among CaCl2, MgCl2 & NaCl thats why it crystallise first on
passing HCl.

73. An element has a body centered cubic (bcc) structure with a cell edge of 288 pm. The
atomic radius is:

4 4 3 2
(1) × 288 pm (2) × 288 pm (3) × 288 pm (4) × 288 pm
3 2 4 4
Sol. 3
For bcc

3 a  4r

3
r=  288 pm
4

74. Which of the following oxoacid of sulphur has –O–O– linkage?

(1) H2S2O8, peroxodisulphuric acid (2) H2S2O7, pyrosulphuric acid
(3) H2SO3, sulphurous acid (4) H2SO4, sulphuric acid
Sol. 1

O
O
S O OH (H2S2O8)
HO O S
O
O

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O O

S S (H2S2O7)
HO O OH
O O

S (H 2SO3)
HO
OH

S (H 2SO4)
HO O
OH
75. Identify the incorrect statement.
(1) Interstitial compounds are those that are formed when small atoms like H, C or N
are trapped inside the crystal lattices of metals.
(2) The oxidation states of chromium in CrO24 and Cr2O72 are not the same.
(3) Cr2+(d4) is a stronger reducing agent than Fe2+(d6) in water.
(4) The transition metals and their compounds are known for their catalytic activity
due to their ability to adopt multiple oxidation states and to form complexes.
Sol. 2
(1) Interstitial compounds are those compounds that are formed when small atoms
like H, B, C or N are trapped inside crystal lattices of metals.
(2) Oxidation state of chromium in CrO42– & Cr2O72– are +6 (same)
(3) Fact
Cr2+ is stronger reducing agent than Fe2+ in water on the basis of standard reduc-
tion potential.
(4) Transition metals are one of the best available catalyst due to their ability to adopt
multiple oxidation states & to form complexes.

76. Which of the following is a cationic detergent?

(1) Cetyltrimethyl ammonium bromide (2) Sodium dodecylbenzene sulphonate
(3) Sodium lauryl sulphate (4) Sodium stearate
Sol. 1
Cetyltrimethyl ammonium bromide is a cationic detergent as it’s hydrophillic part is a
quaternary ammonium ion.

77. The correct option for free expansion of an ideal gas under adiabatic condition is:
(1) q < 0, T = 0 and w = 0 (2) q > 0, T > 0 and w > 0
(3) q = 0, T = 0 and w = 0 (4) q = 0, T < 0 and w > 0
Sol. 3
For an adiabatic process, q = 0
for free expansion, Pext = 0
 w=0
& from First law of Thermodynamics, E = 0
or T = 0

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78. On electrolysis of dil. sulphuric acid using platinum (Pt) electrode, the product ob-
tained at anode will be:
(1) H2S gas (2) SO2 gas (3) Hydrogen gas (4) Oxygen gas
Sol. 4
Anode : 2H2O  O2 + 4H+ + 4e–
Cathode : 2H+ + 2e–  H2(g)
 oxygen gas will be obtained at anode.

79. Identify the correct statement from the following:

(1) Vapour phase refining is carried out for Nickel by Van Arkel method.
(2) Pig iron can be moulded into a variety of shapes.
(3) Wrought iron is impure iron with 4% carbon.
(4) Blister copper has blistered appearance due to evolution of CO2.
Sol. 2
(1) Vapour phase refining is carried out for nickel by Mond process.
(2) Pig iron is molten iron obtained from blast furnace after smelting it can be moulded
into variety of shapes.
(3) Wrought iron is the purest form of iron which has less than 4% carbon.
(4) Blister copper has blistered appearance due to evolution of SO2.

80. Which of the following is a basic amino acid?

(1) Tyrosine (2) Lysine (3) Serine (4) Alanine
Sol. 2

(Lysine)

Basic part is more than acidic part so lysine is basic amino acid.

81. Identify the incorrect match.

Name IUPAC Official Name
(a) Unnilunium (i) Mendelvium
(b) Unniltrium (ii) Lawrencium
(c) Unnilhexium (iii) Seaborgium
(d) Unununnium (iv) Darmstadtium
(1) (c), (iii) (2) (d), (iv) (3) (a), (i) (4) (b), (ii)
Sol. 2
101 - Unnilunium - Mendelevium
103 - Unniltrium - Lawrencium
106 - Unnilhexium - Seaborgium
111 - Unununium - Roentgenium
110 - Ununnilium - Darmstadtium

82. Which of the following alkane cannot be made in good yield by Wurtz reaction?
(1) n-Heptane (2) n-Butane
(3) n-Hexane ((4) 2,3-Dimethylbutane
Sol. 1
Wurtz reaction is used to prepare symmetrical alkane.
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83. Elimination reaction of 2-Bromo-pentane to form pent-2-ene is:

(a) -Elimination reaction (b) Follows Zaitsev rule
(c) Dehydrohalogenation reaction (d) Dehydration reaction
(1) (b), (c), (d) (2) (a), (b), (d) (3) (a), (b), (c) (4) (a), (c), (d)
Sol. 3

In the reaction (i) Dehydrohalogenation

(ii)  - elimination reaction
(iii) follows zaitsev rule (highly substituted alkene is formed as major product)

84. The number of Faradays (F) required to produce 20g of calcium from molten CaCl2
(Atomic mass of Ca = 40 g mol–1) is:
(1) 3 (2) 4 (3) 1 (4) 2
Sol. 3
EquivalentCa = Equivalentcurrent

W
  nf = No. of Faradays
MM

20
 No. of Faradays = 2
40
 No. of Faradays = 1

85. Which one of the followings has maximum number of atoms?

(1) 1g of O2(g) (Atomic mass of O=16)
(2) 1g of Li(s) (Atomic mass of Li=7)
(3) 1g of Ag(s) (Atomic mass of Ag = 108)
(4) 1g of Mg(s) (Atomic mass of Mg = 24)
Sol. 2
1
(1) no. of atoms =  2  NA
32
1
(2) no. of atoms =  NA
7

1
(3) no. of atoms =  NA
108

1
(4) no. of atoms =  NA
24
 1 gm of Li is having maximum no. of atoms.

86. For the reaction, 2Cl(g)  Cl2(g), the correct option is:
(1) rH < 0 and rS > 0 (2) rH < 0 and rS < 0
(3) rH > 0 and rS > 0 (4) rH > 0 and rS < 0

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Sol. 2
2Cl(g)  Cl2(g) + Heat
Due to bond formation stability increases which results in release of heat.
 Hr = –ve or exothermic process
Hr < O
& S < O, because number of Cl atoms decreases in the formation of Cl2(g)

87. Identify the correct statements from the following:

(a) CO2(g) is used as refrigerant for ice-cream and frozen food.
(b) The structure of C60 contains twelve six carbon rings and twenty five carbon rings.
(c) ZSM-5, a type of zeolite, is used to convert alcohols into gasoline.
(d) CO is colourless and odourless gas.
(1) (b) and (c) only (2) (c) and (d) only
(3) (a), (b) and (c) only (4) (a) and (c) only
Sol. 2
 CO2 (s) is not used as refrigerant for ice-cream & frozen food.
six carbon rings – 20
 C60
five carbon rings – 12
 ZSM-5 zeolite used to convert alcohols into gasoline
 CO is colourless & odourless gas

88. Measuring Zeta potential is useful in determining which property of colloidal solution?
(1) Stability of the colloidal particles (2) Size of the colloidal particles
(3) Viscosity (4) Solubility
Sol. 1
A large +ve or –ve value of Zeta potential indicate good stability of the colloidal par-
ticles.

89. What is the change in oxidation number of carbon in the following reaction?
CH4(g) + 4Cl2(g)  CCl4(l) + 4HCl(g)
(1) –4 to +4 (2) 0 to –4 (3) +4 to +4 (4) 0 to +4
Sol. 1

90. The following metal ion activates many enzymes, participates in the oxidation of glu-
cose to produce ATP and with Na, is responsible for the transmission of nerve signals.
(1) Calcium (2) Potassium (3) Iron (4) Copper
Sol. 2
Potassium

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