NEET 2020 — Chemistry

All 45 Chemistry questions we hold from this paper, of the 180 on the site for this sitting — every option and the answer key. 4 marks each, −1 for a wrong answer.

Chemistry

45 questions, one correct option each. +4 for a correct answer, −1 for a wrong one, nothing for a blank.

Q1 open Chemical Bonding and Molecular Structure · Molecular orbital theory

Identify a molecule which does not exist.

A. $H e_{2}$ ✓
B. $L i_{2}$
C. $C_{2}$
D. $O_{2}$

The worked solution is part of a paid pack.

Q2 open Equilibrium · Solubility product and common-ion effect

Find the solubility of $Ni (OH)_{2}$ in 0.1 M NaOH. Given that the ionic product of $Ni (OH)_{2}$ is $2 \times 1 0^{- 15}$ .

A. $2 \times 1 0^{- 13}$ M✓
B. $2 \times 1 0^{- 8}$ M
C. $1 \times 1 0^{- 13}$ M
D. $1 \times 1 0^{8}$ M

The worked solution is part of a paid pack.

Q3 open

Identify the correct statements from the following:

(a) $C O_{2} (g)$ is used as a refrigerant for ice cream and frozen food.

(b) The structure of $C_{60}$ contains twelve six-membered rings and twenty five-membered rings.

(d) CO is a colourless and odourless gas.

A.(a), (b) and (c) only
B.(a) and (c) only
C.(b) and (c) only
D.(c) and (d) only✓

The worked solution is part of a paid pack.

Q4 open Thermodynamics · Entropy and Gibbs energy, spontaneity

Hydrolysis of sucrose is given by the following reaction:

$Sucrose + H_{2} O ⇌ Glucose + Fructose$

If the equilibrium constant ( $K_{C}$ ) is $2 \times 1 0^{13}$ at 300 K, the value of $Δ_{r} G^{\circ}$ at the same temperature will be:

A. $- 8.314 J mo l^{- 1} K^{- 1} \times 300 K \times ln (2 \times 1 0^{13})$ ✓
B. $8.314 J mo l^{- 1} K^{- 1} \times 300 K \times ln (2 \times 1 0^{13})$
C. $8.314 J mo l^{- 1} K^{- 1} \times 300 K \times ln (3 \times 1 0^{13})$
D. $- 8.314 J mo l^{- 1} K^{- 1} \times 300 K \times ln (4 \times 1 0^{13})$

The worked solution is part of a paid pack.

Q5 open Hydrocarbons · Aromatic hydrocarbons: electrophilic substitution, directing effects

Identify compound X in the following sequence of reactions.

Question 95 as printed in the NEET 2020 booklet

A.Chlorobenzene
B.Benzyl chloride ( $C_{6} H_{5} C H_{2} Cl$ )
C.Benzal chloride ( $C_{6} H_{5} CHC l_{2}$ )✓
D.Benzotrichloride ( $C_{6} H_{5} CC l_{3}$ )

The worked solution is part of a paid pack.

Q6 open The d- and f-Block Elements · Lanthanoids and actinoids

Identify the incorrect match.

Name	IUPAC official name
(a) Unnilunium	(i) Mendelevium
(b) Unniltrium	(ii) Lawrencium
(c) Unnilhexium	(iii) Seaborgium
(d) Unununnium	(iv) Darmstadtium

A.(a), (i)
B.(b), (ii)
C.(c), (iii)
D.(d), (iv)✓

The worked solution is part of a paid pack.

Q7 open

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

A. $\frac{3}{4} \times 288$ pm✓
B. $\frac{2}{4} \times 288$ pm
C. $\frac{4}{3} \times 288$ pm
D. $\frac{4}{2} \times 288$ pm

The worked solution is part of a paid pack.

Q8 open Chemical Bonding and Molecular Structure · Hydrogen bonding and dipole moment

Which of the following sets of molecules will have zero dipole moment?

A.Ammonia, beryllium difluoride, water, 1,4-dichlorobenzene
B.Boron trifluoride, hydrogen fluoride, carbon dioxide, 1,3-dichlorobenzene
C.Nitrogen trifluoride, beryllium difluoride, water, 1,3-dichlorobenzene
D.Boron trifluoride, beryllium difluoride, carbon dioxide, 1,4-dichlorobenzene✓

The worked solution is part of a paid pack.

Q9 open Electrochemistry · Electrolysis and Faraday's laws; batteries and corrosion

On electrolysis of dilute sulphuric acid using platinum (Pt) electrodes, the product obtained at the anode will be:

A.Hydrogen gas
B.Oxygen gas✓
C. $H_{2} S$ gas
D. $S O_{2}$ gas

The worked solution is part of a paid pack.

Q10 open Aldehydes, Ketones and Carboxylic Acids · Nucleophilic addition reactions

The reaction between acetone and methylmagnesium chloride, followed by hydrolysis, will give:

A.Isopropyl alcohol
B.Sec-butyl alcohol
C.Tert-butyl alcohol✓
D.Isobutyl alcohol

The worked solution is part of a paid pack.

Q11 open The p-Block Elements · Group 15 and 16: nitrogen, oxygen families

Which of the following oxoacids of sulphur has a $- O - O -$ linkage?

A. $H_{2} S O_{3}$ , sulphurous acid
B. $H_{2} S O_{4}$ , sulphuric acid
C. $H_{2} S_{2} O_{8}$ , peroxodisulphuric acid✓
D. $H_{2} S_{2} O_{7}$ , pyrosulphuric acid

The worked solution is part of a paid pack.

Q12 open Amines · Basicity of amines

Which of the following amines will give the carbylamine test?

Question 102 as printed in the NEET 2020 booklet

A.Aniline ( $C_{6} H_{5} N H_{2}$ )✓
B.N-methylaniline ( $C_{6} H_{5} NHC H_{3}$ )
C.N,N-dimethylaniline ( $C_{6} H_{5} N (C H_{3})_{2}$ )
D.N-ethylaniline ( $C_{6} H_{5} NH C_{2} H_{5}$ )

The worked solution is part of a paid pack.

Q13 open Coordination Compounds · Valence bond and crystal field theory

The calculated spin-only magnetic moment of the $C r^{2 +}$ ion is:

A.3.87 BM
B.4.90 BM✓
C.5.92 BM
D.2.84 BM

The worked solution is part of a paid pack.

Q14 open Thermodynamics · First law, enthalpy and Hess's law

The correct option for the free expansion of an ideal gas under adiabatic conditions is:

A. $q = 0, Δ T = 0$ and $w = 0$ ✓
B. $q = 0, Δ T < 0$ and $w > 0$
C. $q < 0, Δ T = 0$ and $w = 0$
D. $q > 0, Δ T > 0$ and $w > 0$

The worked solution is part of a paid pack.

Q15 open Solutions · Colligative properties

The freezing-point depression constant ( $K_{f}$ ) of benzene is $5.12 K kg mo l^{- 1}$ . The freezing-point depression for a solution of molality 0.078 m containing a non-electrolyte solute in benzene is (rounded to two decimal places):

A.0.20 K
B.0.80 K
C.0.40 K✓
D.0.60 K

The worked solution is part of a paid pack.

Q16 open Electrochemistry · Electrolysis and Faraday's laws; batteries and corrosion

The number of faradays ( $F$ ) required to produce 20 g of calcium from molten $CaC l_{2}$ (atomic mass of Ca = 40 g mol⁻ $^{1})$ is:

A.1✓
B.2
C.3
D.4

The worked solution is part of a paid pack.

Q17 open Aldehydes, Ketones and Carboxylic Acids · Named reactions: aldol, Cannizzaro, Clemmensen, Wolff–Kishner

The reaction between benzaldehyde and acetophenone in the presence of dilute NaOH is known as:

A.Aldol condensation
B.Cannizzaro's reaction
C.Cross-Cannizzaro's reaction
D.Cross-aldol condensation✓

The worked solution is part of a paid pack.

Q18 open Purification and Characterisation of Organic Compounds · Purification methods: crystallisation, distillation, chromatography

Paper chromatography is an example of:

A.Adsorption chromatography
B.Partition chromatography✓
C.Thin-layer chromatography
D.Column chromatography

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Q19 open Chemical Kinetics · Rate law, order and molecularity

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

A.Activation energy
B.Heat of reaction
C.Threshold energy
D.Collision frequency✓

The worked solution is part of a paid pack.

Q20 open Some Basic Concepts of Chemistry · Mole concept and molar mass

A mixture of $N_{2}$ and Ar gases in a cylinder contains 7 g of $N_{2}$ 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 $N_{2}$ is: (atomic masses in g mol⁻ $^{1} : N = 14$ , Ar = 40)

A.9 bar
B.12 bar
C.15 bar✓
D.18 bar

The worked solution is part of a paid pack.

Q21 open

Identify the correct statement from the following:

A.Wrought iron is impure iron with 4% carbon
B.Blister copper has a blistered appearance due to the evolution of $C O_{2}$
C.Vapour-phase refining is carried out for nickel by the Van Arkel method
D.Pig iron can be moulded into a variety of shapes✓

The worked solution is part of a paid pack.

Q22 open Organic Chemistry: Some Basic Principles and Techniques · Electronic effects: inductive, resonance, hyperconjugation

A tertiary-butyl carbocation is more stable than a secondary-butyl carbocation because of:

A.The $- I$ effect of $- C H_{3}$ groups
B.The $+ R$ effect of $- C H_{3}$ groups
C.The $- R$ effect of $- C H_{3}$ groups
D.Hyperconjugation✓

The worked solution is part of a paid pack.

Q23 open

Which of the following is a cationic detergent?

A.Sodium lauryl sulphate
B.Sodium stearate
C.Cetyltrimethylammonium bromide✓
D.Sodium dodecylbenzene sulphonate

The worked solution is part of a paid pack.

Q24 open Haloalkanes and Haloarenes · Nucleophilic substitution: SN1 and SN2

The elimination reaction of 2-bromopentane to form pent-2-ene is:

$(a) A β -$ elimination reaction

(b) In accordance with Zaitsev's rule

(d) A dehydration reaction

A.(a), (b), (c)✓
B.(a), (c), (d)
C.(b), (c), (d)
D.(a), (b), (d)

The worked solution is part of a paid pack.

Q25 open Solutions · Concentration terms, Henry's and Raoult's laws

The mixture which shows positive deviation from Raoult's law is:

A.Ethanol + acetone✓
B.Benzene + toluene
C.Acetone + chloroform
D.Chloroethane + bromoethane

The worked solution is part of a paid pack.

Q26 open Coordination Compounds · Valence bond and crystal field theory

Which of the following is the correct order of increasing field strength of ligands in forming coordination compounds?

A. $SC N^{-} < F^{-} < C_{2} O_{4}^{2 -} < C N^{-}$ ✓
B. $SC N^{-} < F^{-} < C N^{-} < C_{2} O_{4}^{2 -}$
C. $F^{-} < SC N^{-} < C_{2} O_{4}^{2 -} < C N^{-}$
D. $C N^{-} < C_{2} O_{4}^{2 -} < SC N^{-} < F^{-}$

The worked solution is part of a paid pack.

Q27 open Biomolecules · Proteins, enzymes and vitamins

Which of the following is a basic amino acid?

A.Serine
B.Alanine
C.Tyrosine
D.Lysine✓

The worked solution is part of a paid pack.

Q28 open

HCl gas was passed through a solution containing $CaC l_{2}$ , $MgC l_{2}$ and NaCl. Which compound(s) crystallise(s) out?

A.Both $MgC l_{2}$ and $CaC l_{2}$
B.Only NaCl✓
C.Only $MgC l_{2}$
D. $NaCl$ , $MgC l_{2}$ and $CaC l_{2}$

The worked solution is part of a paid pack.

Q29 open

Which of the following is a natural polymer?

A.cis-1,4-Polyisoprene✓
B.Poly(butadiene-styrene)
C.Polybutadiene
D.Poly(butadiene-acrylonitrile)

The worked solution is part of a paid pack.

Q30 open

Which of the following is not correct about carbon monoxide?

A.It forms carboxyhaemoglobin
B.It reduces the oxygen-carrying ability of blood
C.Carboxyhaemoglobin (haemoglobin bound to CO) is less stable than oxyhaemoglobin✓
D.It is produced due to incomplete combustion

The worked solution is part of a paid pack.

Q31 open Biomolecules · Carbohydrates

Sucrose on hydrolysis gives:

A. $β$ -D-glucose + $α$ -D-fructose
B. $α$ -D-glucose + $β$ -D-glucose
C. $α$ -D-glucose + $β$ -D-fructose✓
D. $α$ -D-fructose + $β$ -D-fructose

The worked solution is part of a paid pack.

Q32 open Biomolecules · Proteins, enzymes and vitamins

The following metal ion activates many enzymes, participates in the oxidation of glucose to produce ATP, and, with sodium, is responsible for the transmission of nerve signals.

A.Iron
B.Copper
C.Calcium
D.Potassium✓

The worked solution is part of a paid pack.

Q33 open Some Basic Concepts of Chemistry · Mole concept and molar mass

Which one of the following has the maximum number of atoms?

A.1 g of Ag(s) (atomic mass of Ag = 108)
B.1 g of Mg(s) (atomic mass of Mg = 24)
C.1 g of $O_{2} (g)$ (atomic mass of O = 16)
D.1 g of Li(s) (atomic mass of Li = 7)✓

The worked solution is part of a paid pack.

Q34 open Structure of Atom · Electronic configuration, Aufbau, Pauli, Hund

The number of protons, neutrons and electrons in $_{71}^{175} Lu$ , respectively, are:

A.71, 104 and 71✓
B.104, 71 and 71
C.71, 71 and 104
D.175, 104 and 71

The worked solution is part of a paid pack.

Q35 open Redox Reactions · Oxidation number and balancing redox equations

What is the change in the oxidation number of carbon in the following reaction?

$C H_{4} (g) + 4C l_{2} (g) \to CC l_{4} (l) + 4HCl (g)$

A.+4 to +4
B.0 to +4
C. $- 4$ to +4✓
D.0 to $- 4$

The worked solution is part of a paid pack.

Q36 open The d- and f-Block Elements · Transition elements: trends and properties

Identify the incorrect statement.

A. $C r^{2 +}$ ( $d^{4}$ ) is a stronger reducing agent than $F e^{2 +}$ ( $d^{6}$ ) in water
B.Transition metals and their compounds are known for their catalytic activity due to their ability to adopt multiple oxidation states and form complexes
C.Interstitial compounds are those formed when small atoms like H, C or N are trapped inside the crystal lattices of metals
D.The oxidation states of chromium in $Cr O_{4}^{2 -}$ and $C r_{2} O_{7}^{2 -}$ are not the same✓

The worked solution is part of a paid pack.

Q37 open Thermodynamics · Entropy and Gibbs energy, spontaneity

For the reaction $2Cl (g) \to C l_{2} (g)$ , the correct option is:

A. $Δ_{r} H > 0$ and $Δ_{r} S > 0$
B. $Δ_{r} H > 0$ and $Δ_{r} S < 0$
C. $Δ_{r} H < 0$ and $Δ_{r} S > 0$
D. $Δ_{r} H < 0$ and $Δ_{r} S < 0$ ✓

The worked solution is part of a paid pack.

Q38 open

Measuring zeta potential is useful in determining which property of a colloidal solution?

A.Viscosity
B.Solubility
C.Stability of the colloidal particles✓
D.Size of the colloidal particles

The worked solution is part of a paid pack.

Q39 open

Urea reacts with water to form A, which decomposes to form B. B, when passed through $C u^{2 +} (aq)$ , forms a deep-blue-coloured solution C. What is the formula of C from the following?

A. $CuS O_{4}$
B. $[Cu (N H_{3})_{4}]^{2 +}$ ✓
C. $Cu (OH)_{2}$
D. $CuC O_{3} \cdot Cu (OH)_{2}$

The worked solution is part of a paid pack.

Q40 open

Match the following and identify the correct option.

List-I	List-II
(a) $CO (g) + H_{2} (g)$	(i) $Mg (HC O_{3})_{2} + Ca (HC O_{3})_{2}$
(b) Temporary hardness of water	(ii) An electron-deficient hydride
(c) $B_{2} H_{6}$	(iii) Synthesis gas
(d) $H_{2} O_{2}$	(iv) Non-planar structure