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Date : 13-9-2020CHMISTRY

NEET PAPER - 2020

136. On electrolysis of dil. sulphuric acid usingPlatinum (Pt) electrode, the product obtained atanode will be [12th-Electrochemistry]1) Oxygen 2) H2S gas3) SO2 gas 4) Hydrogen gas

Ans : (1)At anode :

4OH– 2H2O + O2 + 4e–

137. The number of Faradays (F) required to produce20 g of calcium from molten CaCl2 (Atomic massof Ca = 40 g mol–1) is : [12th-Electrochemistry]1) 2 2) 3 3) 4 4) 1

Ans : (4)CaCl2 = Ca2+ + 2Cl–

Ca2+ + 2e– Ca1 mol Ca2+ required 2F20 g (1/2 Mole) of Ca2+ required 1F

138. Elimination reaction of 2-Bromo-pentane to formpent-2-ene is [11th-Alkene (Hydrocarbons]a) -Elimination reactionb) Follows Zaitsev rulec) Dehydrohalogenation reactiond) Dehydration reaction1) (a), (c), (d) 2) (b), (c), (d)3) (a), (b), (d) 4) (a), (b), (c)

Ans : (4)

This reaction is dehydrohalogenationThis reaction follows E2 mechanismIt is -Elimination reactionIt follows Saytzeff’s rule or Zaitsev rule.

139. The rate constant for a first order reaction is4.606 × 10–3 s–1. The time required to reduce 2.0g of the reactant to 0.2 g is [12th-Che. Kinetics]1) 200 s 2) 500 s 3) 1000 s 4) 100 s

Ans : (2)

140. Which of the following set of molecules willhave zero dipole moment ? [11th-Che. Bonding]1) Boron trifluoride, hydrogen fluoride, carbondioxide, 1, 3-dichlorobenzene2) Nitrogen trifluoride, beryllium difluoride, water,1, 3-dichlorobenzene3) Boron trifluoride, beryllium difluoride, carbondioxide, 1, 4-dichlorobenzene4) Ammonia, beryllium difluoride, water, 1, 4-dichlorobenzene

Ans : (3)

141. The mixture which shows positive deviationfrom Raoult’s law is : [12th-Solution]1) Benzene + Toluene2) Acetone + Chloroform3) Chloroethane + Bromoethane4) Ethanol + Acetone

Ans : (4) Ethanol + Acetone shows +ve deviation fromideal behaviour.

142. Sucrose on hydrolysis gives : [12th-Biomolecule]1) -D-Glucose + -D-Glucose2) -D-Glucose + -D-Fructose3) -D-Fructose + -D-Fructose4) -D-Glucose + -D-Fructose

G 6Time : 2pm to 5pm

Paper +Hints & Solution

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Ans : (2)

Sucrose Hydrolysis -D-Glucose + -D-Fructose

143. Which of the following is a basic amino acid ?[12th-Biomolecule]

1) Alanine 2) Tyrosine 3) Lysine 4) SerineAns : (3)

Lysine has two –NH2 groups so it is basic amino acid.144. Which of the following alkane cannot be made

in good yield by Wurtz reaction ?[11th-Hydrocarbon]

1) 2, 3-Dimethylbutane 2) n-Heptane3) n-Butane 4) n-Hexane

Ans : (2)n-Heptane is an assymetric alkane, so Wurtz reactionis not fruitful.

145. Which of the following is a cationic detergent ?[12th-Che. in everyday life]

1) Sodium stearate2) Cetyltrimethyl ammonium bromide3) Sodium dodecylbenzene sulphonate4) Sodium lauryl sulphate

Ans : (2)

146. Which of the following amine will give thecarbylamine test ? [12th-Nitro. Containing Comp.]

1) 2)

3) 4)

Ans : (4)Only primary amine responds in carbylamine test.

147. Paper chromatography is an example of :[12th-Qualitative analysis]

1) Partition chromatography2) Thin layer chromatography3) Column chromatography4) Adsorption chromatography

Ans : (1)Paper chromatography is an example of parititionchromatography.

148. Find out the solubility of Ni(OH)2 in 0.1 MNaOH. Given that the ionic product of Ni(OH)2

is 2 × 10–15. [11th-Che. equilibrium]1) 2 × 10–8 M 2) 1 × 10–13 M3) 1 × 108 M 4) 2 × 10–13 M

Ans : (4)

149. Which one of the following has maximumnumber of atoms ? [11th-Mole Concept]1) 1 g of Mg(s) [Atomic mass of Mg = 24]2) 1 g of O2(g) [Atomic mass of O = 16]3) 1 g of Li(s) [Atomic mass of Li = 7]4) 1 g of Ag(s) [Atomic mass of Ag = 108]

Ans : (3)

150. For the reaction, 2Cl(g) Cl2(g), the correctoption is [11th-Thermodynamics]1) rH > 0 and rS < 02) rH < 0 and rS > 03) rH < 0 and rS < 04) rH > 0 and rS > 0

Ans : (3)

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151. What is the change in oxidation number ofcarbon in the following reaction

CH4(g) + 4Cl2(g) CCl4(l) + 4HCl(g)[11th-Redox Reaction]

1) 0 to +4 2) –4 to +43) 0 to –4 4) +4 to +4

Ans : (2)

152. Which of the following is a natural polymer ?[12th-Polymer]

1) poly (Butadiene-styrene)2) polybutadiene3) poly (Butadiene-acrylonitrile)4) cis-1, 4-polyisoprene

Ans : (4)cis-1, 4-isoprene is the monomer of natural rubber.

153. The calculated spin only magnetic mometn ofCr2+ ion is : [12th-d-block/Atomic structure]1) 4.90 BM 2) 5.92 BM3) 2.84 BM 4) 3.87 BM

Ans : (1)Cr = 1s2 2s2 2p6 3s2 3p6 3d5 4s1

Cr2+ = 1s2 2s2 2p6 3s2 3p6 3d4

4 unpaired electrons

Spin only magnetic moment = n(n + 2) BM

= 4(6) BM

= 24 BM

= 4.9 BM154. Urea reacts with water to form A which will

decompose to form B. B when passed throughCu2+(aq), deep blue colour solution C is formed.What is the formula of C from the following ?

[12th-Co-ordination compound]1) [Cu(NH3)4]2+ 2) Cu(OH)2

3) CuCO3.Cu(OH)2 4) CuSO4

Ans : (1)

155. The following metal ion activates manyenzymes, participates in the oxidation of glucoseto produce ATP and with Na, is responsible forthe transmission of nerve signals.

[11th-s-block]1) Copper 2) Calcium3) Potassium 4) Iron

Ans : (3)Thus potassium ions are the most abundant cationswithin cell fluids, where they activate many enzymes.

156. Hydrolysis of sucrose is given by the followingreaction

Sucrose + H2O Glucose + FructoseIf the equilibrium constant (Kc) is 2 × 1013 at 300K, the value of rG– at the same temperture willbe : [11th-Che. Equilibrium]1) 8.314 J mol–1 K–1 × 300 K × ln (2 × 1013)2) 8.314 J mol–1 K–1 × 300 K × ln (3 × 1013)3) –8.314 J mol–1 K–1 × 300 K × ln (4 × 1013)4) –8.314 J mol–1 K–1 × 300 K × ln (2 × 1013)

Ans : (4)Go = –RT ln KGo = –8.314 J mol–1 K–1 × 300 K × ln (2 × 1013)

157. An increase in the concentration of the reactantsof a reaction leads to change in

[12th-Che. Kinetics]1) Heat of reaction 2) Threshold energy3) Collision frequency 4) Activation energy

Ans : (3)Increase in the concentration of the reactants of thereaction will increase collision frequency.

158. Measuring Zeta potential is useful indetermining which property of colloidalsolution ? [12th-Surface Chemistry]1) Solubility2) Stability of the colloidal particles3) Size of the colloidal particles4) Viscosity

Ans : (2)By using Zeta potential we can determine stabilityof the colloidal particles.

159. Reaction between acetone andmethylmagnesium chloride followed byhydrolysis will give : [12th-Alc. Phe & Ether]1) Sec. butyl alcohol 2) Tert. butyl alcohol3) Isobutyl alcohol 4) Isopropyl alcohol

Ans : (2)

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160. HCl was passed through a solution of CaCl2,MgCl2 and NaCl. Which of the followingcompound(s) crystallise(s) ?

[11th-s-Block]1) Only NaCl2) Only MgCl2

3) NaCl, MgCl2 and CaCl2

4) Both MgCl2 and CaCl2

Ans : (1)CaCl2 and MgCl2 are more soluble than NaCl henceNaCl crystallises.

161. The number of protons, neutrons and electrons

in 175

71Lu , respectively, are [11th-Mole concepts]1) 104, 71 and 71 2) 71, 71 and 1043) 175, 104 and 71 4) 71, 104 and 71

Ans : (4)175 71LuNo. of protons = 71No. of neutrons = 175 – 71 104No. of electrons = 71

162. Match the following :Oxide Nature

a) CO (i) Basicb) BaO (ii) Neutralc) Al2O3 (iii) Acidicd) Cl2O7 (iv) AmphotericWhich of the following is correct option ?

[11th-Periodic Classification](a) (b) (c) (d)

1) (ii) (i) (iv) (iii)2) (iii) (iv) (i) (ii)3) (iv) (iii) (ii) (i)4) (i) (ii) (iii) (iv)

Ans : (1)CO – Neutral oxideBaO – Basic oxideAl2O3 – AmphotericCl2O7 – Acidic oxide

163. An element has a body centetred cubic (bcc)

strcture with a cell edge of 288 pm. The atomicradius is : [12th-Solid state]

1) 24

× 288 pm 2) 43

× 288 pm

3) 42

× 288 pm 4) 34

× 288 pm

Ans : (4) In BCC

4r = 3 a (a = 288 pm)

r = 34

a

r = 34

× 288 pm

164. A mixture of N2 and Ar gases in a cylindercontains 7 g of N2 and 8 g of Ar. If the totalpressure of the mixture of the gases in thecylinder is 27 bar, the partial pressure of N2 is[Use atomic massses (in g mol–1) : N = 14, Ar = 40]

[11th-States of Matter]1) 12 bar 2) 15 bar 3) 18 bar 4) 9 bar

Ans : (2)Mass of N2 = 7 gram

Moles of N2 = 728 = 0.25 mol

Mass of Ar = 8g

Moles of Ar = 8

40 = 0.2 mol

Total pressure = 27 barPartial partial = Mole fraction × Total pressurePN2

= XN2 × PTotal

= 0.25

0.25 0.2× 27 = 15 bar

165. Which of the following is the correct order ofincreasing field strength of ligands to formcoordination compounds ?

[12th-Co-ordination Comp]1) SCN– < F– < CN– < C2O4

2–

2) F– < SCN– < C2O42– < CN–

3) CN– < C2O42– < SCN– < F–

4) SCN– < F– < C2O42– < CN–

Ans : (4) Increasing ligand field StrengthSCN– < F– < C2O4

2– < CN–

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166. Anisole on cleavage with HI gives :[12th-Alc. Phen & ether]

1) 2)

3) 4)

Ans : (4)

167. The correct option for free expansion of an idealgas under adiabatic condition is :

[11th-Thermodynamics]1) q = 0, T < 0 and w > 02) q < 0, T = 0 and w = 03) q > 0, T > 0 and w > 04) q = 0, T = 0 and w = 0

Ans : (4) For Adiabatic free expansion of idal gasq = 0w = 0T = 0

168. Identify the correct statement from the following[12th-Metallurgy]

1) Bister copper has blistered appearance due toevolution of CO2.2) Vapour phase refining is carried out for Nickel byVan Arkel method3) Pig iron can be moulded into a variety of shapes4) Wrought iron is impure iron with 4% carbon

Ans : (3) Pig iron can be moulded into a variety of shapes169. Identify the incorrect statement

[12th-d-block]1) The transition metals and their compounds areknown for their catalytic activity due to their ability ofadopt multiple oxidation states and to form complexes2) Interstitial compounds are those that are formedwhen small atoms like H, C or N are trapped insidethe crystal lattices of metals3) The oxidation states of chromium in CrO4

2– andCr2O7

2– are not the same4) Cr2+(d4) is a stronger reducing agent than Fe2+(d6)in water

Ans : (3)Correct Statement : 1) The transition metals and theircompounds are known for their catalytic activity due to

their ability of adopt multiple oxidation states and to formcomplexesCorrect Statement : 2) Generally non metals like H,C, N, O ... are trapped inside the crystal lalticeIncorrect Statement : 3) CrO4

2– oxidtion state of Cr = +6Cr2O7

2– oxidation state of Cr = +6Both are sameCorrect Statement : 4) Cr2+ (d4) Cr3+ (d3) + e–

(stable)Cr2+ good reducing agnet

Fe2+(d6) Fe3+(d5) + e Stable unstable

Fe2+ weak reducing agent170. Identify compound X in the following sequence

of reactions : [11th-Hydrocarbon]

1) 2)

3) 4)

Ans : (2)

171. Match the following and identify the correctoptiona) CO(g) + H2(g) i) Mg(HCO3)2 + Ca(HCO3)2

b) Temporary hardness ii) An electron deficient of water hydridec) B2H6 iii) Synthesis gasd) H2O2 iv) Non-planar structure

[11th-Hydrogen](a) (b) (c) (d)

1) (iii) (ii) (i) (iv)2) (iii) (iv) (ii) (i)3) (i) (iii) (ii) (iv)4) (iii) (i) (ii) (iv)

Ans : (4) CO + H2 = Synthesis gasTemporary hardness of water due to Mg(HCO3)2 +

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B2H6 is an electron deficient hydrideH2O2 is non planar due to ‘‘O’’ has sp3 hybridisation

172. The freezing point depression constant (Kf) ofbenzene is 5.12 K kg mol–1. The freezing pointdepression for the solution of molality 0.078 mcontaining a non-electrolyte solute in benzeneis (rounded off upto two decimal places) :

[12th-Solution & Colligative prop.]1) 0.80 K 2) 0.40 K 3) 0.60 K 4) 0.20 K

Ans : (2) Tf = Kf mTf = 5.12 K kg mol–1 × 0.078 mol kg–1 = 0.4 K

173. A tertiary butyl carbocation is more stable thana secondary butyl carbocation because of whichof the following ? [11th-GOC]1) +R effect of –CH3 groups2) –R effect fo –CH3 groups3) Hyperconjugation4) –I effect of –CH3 groups

Ans : (3)

No. of hyperconjugating hydrogens in I = 9No. of hyperconjugating hydrogen in II = 5more the hyperconjugating hydrogens more will bethe stability

174. An alkene on ozonolysis gives methanal as oneof the product. Its structure is :

[11th-Hydrocarbon]

1) 2)

3) 4)

Ans :(2)

Terminal alkenes on ozonolysis give methanal(formaldehyde) formed

175. Which of the following is not correct aboutcarbon monoxide ? [11th-p-Block]1) It reduces oxygen carrying ability of blood2) The carboxyhemoglobin (haemoglobin bound toCO) is less stable than oxyhaemoglobin3) It is produced due to incomplete combustion4) It forms carboxyhaemoglobin

Ans : (2) The carboxyhaemoglobin is 300 times more stablethan oxyhaemoglobin

176. Identify a molecule which does not exist[11th-Che. Bonding]

1) Li2 2) C2 3) O2 4) He2

Ans : (4) The molecule bond order is zero. The moleculedoes not existHe2 : 1s

2 1s2

B.O = 12 [2–2] 0

177. Which of the following oxoacid of sulphur has– O – O – linkage ? [12th-p-Block]1) H2SO4, sulphuric acid2) H2S2O8, peroxodisulphuric acid3) H2S2O7, pyrosulphuric acid4) H2SO3, sulphurous acid

Ans : (2) peroxodisulphurie acid (Marshall’s acid)

178. Identify the correct statements from the followinga) CO2(g) is used as refrigerant for ice-cream andfrozen foodb) The structure of C60 Contains twelve six carbonrings and twenty five carbon ringsc) ZSM-5, a type of zeolite, is used to convertalcohols into gasolined) CO is colorless and odourless gas

[11th-p-Block & Surface Che.]1) (a) and (c) only2) (b) and (c) only3) (c) and (d) only4) (a), (b) and (c) only

Ans : (3)

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a) CO2(g) is not used for refigesationb) C60 contains ‘20’ six membered ring, 12 fivemembered ringc) ZSM–5 zeolite is used to convert alcohols intogasolined) CO is colour less and smell less

179. Reaction between benzaldehyde andacetophenone in presence of dilute NaOH isknown as : [12th-Carbonyl Comp.]1) Cannizzaro’s reaction2) Cross cannizzaro’s reaction3) Cross Aldol condensation4) Aldol condensation

Ans : (3)

180. Identify the incorrect match Name IUPAC Official Name

a) Unnilunium i) Mendelviumb) Unniltrium ii) Lawrenciumc) Unnilhexium iii) Seaborgiumd) Unununnium iv) Darmstadtium

[11th-Periodic Classification / f-block]1) (b), (ii) 2) (c), (iii) 3) (d), (iv) 4) (a), (i)

Ans : (3) Unununnium - 111 - Rontagenium