NEET 2019 — Chemistry

All 42 Chemistry questions we hold from this paper, of the 176 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 Hydrocarbons · Alkenes and alkynes: addition reactions, Markovnikov

The number of sigma ( $σ$ ) and pi ( $π$ ) bonds in pent-2-en-4-yne ( $C H_{3} - CH = CH - C \equiv CH$ ) is:

A.10 $σ$ bonds and 3 $π$ bonds✓
B.8 $σ$ bonds and 5 $π$ bonds
C.11 $σ$ bonds and 2 $π$ bonds
D.13 $σ$ bonds and no $π$ bonds

The worked solution is part of a paid pack.

Q2 open Structure of Atom · Electronic configuration, Aufbau, Pauli, Hund

4d, 5p, 5f and 6p orbitals are arranged in order of decreasing energy. The correct option is:

A. $5 f > 6 p > 5 p > 4 d$ ✓
B. $6 p > 5 f > 5 p > 4 d$
C. $6 p > 5 f > 4 d > 5 p$
D. $5 f > 6 p > 4 d > 5 p$

The worked solution is part of a paid pack.

Q3 open Redox Reactions · Types of redox reactions

Which of the following reactions are disproportionation reactions?

(a) $2 C u^{+} \to C u^{2 +} + C u^{0}$

(b) $3 Mn O_{4}^{2 -} + 4 H^{+} \to 2Mn O_{4}^{-} + Mn O_{2} + 2 H_{2} O$

(d) $2 Mn O_{4}^{-} + 3M n^{2 +} + 2 H_{2} O \to 5Mn O_{2} + 4 H^{+}$

Select the correct option:

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

The worked solution is part of a paid pack.

Q4 open Thermodynamics · First law, enthalpy and Hess's law

Under isothermal conditions, a gas at 300 K expands from 0.1 L to 0.25 L against a constant external pressure of 2 bar. The work done BY the gas is: (Given: 1 L bar = 100 J)

A. $- 30$ J
B.5 kJ
C.25 J
D.30 J✓

The worked solution is part of a paid pack.

Q5 open

Among the following, the one that is not a greenhouse gas is:

A.Nitrous oxide
B.Methane
C.Ozone
D.Sulphur dioxide✓

The worked solution is part of a paid pack.

Q6 open Electrochemistry · Electrochemical cells and Nernst equation

For the cell reaction $2 F e^{3 +} (aq) + 2 I^{-} (aq) \to 2F e^{2 +} (aq) + I_{2} (aq)$ , $E_{ce l l}^{⊖} = 0.24$ V at 298 K. The standard Gibbs energy ( $Δ_{r} G^{⊖}$ ) of the cell reaction is: (Given: Faraday constant $F = 96500 C mo l^{- 1}$ )

A. $- 46.32 kJ mo l^{- 1}$ ✓
B. $- 23.16 kJ mo l^{- 1}$
C. $46.32 kJ mo l^{- 1}$
D. $23.16 kJ mo l^{- 1}$

The worked solution is part of a paid pack.

Q7 open Biomolecules · Proteins, enzymes and vitamins

Enzymes that utilise ATP in phosphate transfer require an alkaline earth metal (M) as a cofactor. M is:

A.Be
B.Mg✓
C.Ca
D.Sr

The worked solution is part of a paid pack.

Q8 open Hydrocarbons · Alkenes and alkynes: addition reactions, Markovnikov

The most suitable reagent for converting but-2-yne ( $H_{3} C - C \equiv C - C H_{3}$ ) into cis-2-butene is:

A.Na / liquid $N H_{3}$
B. $H_{2}$ , Pd/C, quinoline (Lindlar's catalyst)✓
C.Zn/HCl
D. $H g^{2 +} / H^{+}$ , $H_{2} O$

The worked solution is part of a paid pack.

Q9 open The p-Block Elements · Group 15 and 16: nitrogen, oxygen families

Which is the correct thermal stability order for $H_{2} E$ (E = O, S, Se, Te, Po)?

A. $H_{2} S < H_{2} O < H_{2} Se < H_{2} Te < H_{2} Po$
B. $H_{2} O < H_{2} S < H_{2} Se < H_{2} Te < H_{2} Po$
C. $H_{2} Po < H_{2} Te < H_{2} Se < H_{2} S < H_{2} O$ ✓
D. $H_{2} Se < H_{2} Te < H_{2} Po < H_{2} O < H_{2} S$

The worked solution is part of a paid pack.

Q10 open The p-Block Elements · Group 13 and 14 elements

Which of the following is an incorrect statement?

A. $Pb F_{4}$ is covalent in nature✓
B. $SiC l_{4}$ is easily hydrolysed
C. $Ge X_{4}$ (X = F, Cl, Br, I) is more stable than $Ge X_{2}$
D. $Sn F_{4}$ is ionic in nature

The worked solution is part of a paid pack.

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

Match the following industrial processes with their principal product, and choose the correct option:

Column I	Column II
(a) Pure nitrogen	(i) Chlorine
(b) Haber process	(ii) Sulphuric acid
(c) Contact process	(iii) Ammonia
(d) Deacon's process	(iv) Sodium/barium azide

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

The worked solution is part of a paid pack.

Q12 open Chemical Bonding and Molecular Structure · Molecular orbital theory

Which of the following diatomic molecular species has only $σ$ bonds according to Molecular Orbital Theory?

A. $O_{2}$
B. $N_{2}$
C. $C_{2}$ ✓
D. $B e_{2}$

The worked solution is part of a paid pack.

Q13 open Classification of Elements and Periodicity in Properties · Periodic trends: radius, ionisation enthalpy, electron gain enthalpy, electronegativity

For the second-period elements, the correct increasing order of first ionisation enthalpy is:

A. $Li < Be < B < C < N < O < F < Ne$
B. $Li < B < Be < C < O < N < F < Ne$ ✓
C. $Li < B < Be < C < N < O < F < Ne$
D. $Li < Be < B < C < O < N < F < Ne$

The worked solution is part of a paid pack.

Q14 open

The biodegradable polymer among the following is:

A.Nylon-6,6
B.Nylon-2-nylon-6✓
C.Nylon-6
D.Buna-S

The worked solution is part of a paid pack.

Q15 open Equilibrium · Solubility product and common-ion effect

The pH of a saturated solution of $Ca (OH)_{2}$ is 9. The solubility product ( $K_{s p}$ ) of $Ca (OH)_{2}$ is:

A. $0.5 \times 1 0^{- 15}$ ✓
B. $0.25 \times 1 0^{- 10}$
C. $0.125 \times 1 0^{- 15}$
D. $0.5 \times 1 0^{- 10}$

The worked solution is part of a paid pack.

Q16 open Chemical Kinetics · Integrated rate equations and half-life

If the rate constant for a first-order reaction is $k$ , the time $t$ required for 99% completion of the reaction is given by:

A. $t = 0.693/ k$
B. $t = 6.909/ k$
C. $t = 4.606/ k$ ✓
D. $t = 2.303/ k$

The worked solution is part of a paid pack.

Q17 open Biomolecules · Proteins, enzymes and vitamins

The non-essential amino acid among the following is:

A.Valine
B.Leucine
C.Alanine✓
D.Lysine

The worked solution is part of a paid pack.

Q18 open Hydrocarbons · Aromatic hydrocarbons: electrophilic substitution, directing effects

Among the following, the reaction that proceeds through electrophilic substitution is:

A.Benzenediazonium chloride + $C u_{2} C l_{2}$ $\to$ chlorobenzene + $N_{2}$ (Sandmeyer reaction)
B.Benzene + $C l_{2}$ , $AlC l_{3}$ $\to$ chlorobenzene + HCl (Friedel–Crafts halogenation)✓
C.Benzene + $C l_{2}$ , UV light $\to$ benzene hexachloride (free-radical addition)
D.Benzyl alcohol + HCl, heat $\to$ benzyl chloride + $H_{2} O$

The worked solution is part of a paid pack.

Q19 open Solutions · Concentration terms, Henry's and Raoult's laws

The mixture that forms a maximum-boiling azeotrope is:

A.Water + nitric acid✓
B.Ethanol + water
C.Acetone + carbon disulphide
D.Heptane + octane

The worked solution is part of a paid pack.

Q20 open Chemical Kinetics · Rate law, order and molecularity

For the chemical reaction $N_{2} (g) + 3 H_{2} (g) ⇌ 2N H_{3} (g)$ , the correct expression relating the rates of disappearance/appearance of each species is:

A. $\frac{1}{3} \frac{d [ H _{2} ]}{d t} = \frac{1}{2} \frac{d [ N H _{3} ]}{d t}$
B. $\frac{d [ N _{2} ]}{d t} = 2 \frac{d [ N H _{3} ]}{d t}$
C. $- \frac{d [ N _{2} ]}{d t} = \frac{1}{2} \frac{d [ N H _{3} ]}{d t}$ ✓
D. $3 \frac{d [ H _{2} ]}{d t} = 2 \frac{d [ N H _{3} ]}{d t}$

The worked solution is part of a paid pack.

Q21 open Some Basic Concepts of Chemistry · Stoichiometry and limiting reagent

The number of moles of hydrogen molecules required to produce 20 moles of ammonia through the Haber process is:

A.10
B.20
C.30✓
D.40

The worked solution is part of a paid pack.

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

The compound that is most difficult to protonate (at the carbonyl oxygen) among the following is:

A.Formaldehyde, $HCHO$
B.Acetaldehyde, $C H_{3} CHO$
C.Acetone, $C H_{3} COC H_{3}$
D.Benzaldehyde, $C_{6} H_{5} CHO$ ✓

The worked solution is part of a paid pack.

Q23 open Solutions · Concentration terms, Henry's and Raoult's laws

For an ideal solution, the correct option (at constant $T$ and $P$ ) is:

A. $Δ_{mi x} S = 0$
B. $Δ_{mi x} V \neq = 0$
C. $Δ_{mi x} H = 0$ ✓
D. $Δ_{mi x} G = 0$

The worked solution is part of a paid pack.

Q24 open Equilibrium · Ionic equilibrium: acids, bases, pH, buffers

The conjugate bases for the Brønsted acids $H_{2} O$ and $HF$ are, respectively:

A. $O H^{-}$ and $H_{2} F^{+}$
B. $H_{3} O^{+}$ and $F^{-}$
C. $O H^{-}$ and $F^{-}$ ✓
D. $H_{3} O^{+}$ and $H_{2} F^{+}$

The worked solution is part of a paid pack.

Q25 open

Among the following, the narrow-spectrum antibiotic is:

A.Penicillin G✓
B.Ampicillin
C.Amoxycillin
D.Chloramphenicol

The worked solution is part of a paid pack.

Q26 open Hydrocarbons · Alkenes and alkynes: addition reactions, Markovnikov

An alkene A, on ozonolysis (reaction with $O_{3}$ followed by Zn/ $H_{2} O$ ), gives propanone and ethanal in equimolar amounts (A is 2-methylbut-2-ene). Addition of HCl to A gives B as the major product (Markovnikov addition). The structure of B is:

A. $Cl - C H_{2} - C H_{2} - CH (C H_{3})_{2}$
B. $H_{3} C - C H_{2} - CH (C H_{2} Cl) - C H_{3}$
C. $H_{3} C - C H_{2} - C (Cl) (C H_{3}) - C H_{3}$ ✓
D. $H_{3} C - CH (Cl) - CH (C H_{3})_{2}$

The worked solution is part of a paid pack.

Q27 open Coordination Compounds · Valence bond and crystal field theory

What is the correct electronic configuration of the central metal ion in $K_{4} [Fe (CN)_{6}]$ , based on crystal field theory?

A. $t_{2 g}^{4} e_{g}^{2}$
B. $t_{2 g}^{6} e_{g}^{0}$ ✓
C. $e^{3} t_{2}^{3}$
D. $e^{4} t_{2}^{2}$

The worked solution is part of a paid pack.

Q28 open Chemical Bonding and Molecular Structure · VSEPR and molecular shapes

Identify the incorrect statement related to $PC l_{5}$ from the following:

A.The three equatorial P–Cl bonds make an angle of $12 0^{\circ}$ with each other
B.The two axial P–Cl bonds make an angle of $18 0^{\circ}$ with each other
C.Axial P–Cl bonds are longer than equatorial P–Cl bonds
D. $PC l_{5}$ molecule is non-reactive✓

The worked solution is part of a paid pack.

Q29 open Equilibrium · Ionic equilibrium: acids, bases, pH, buffers

Which of the following mixtures will make a basic buffer?

A.50 mL of 0.1 M NaOH + 25 mL of 0.1 M $C H_{3} COOH$
B.100 mL of 0.1 M $C H_{3} COOH$ + 100 mL of 0.1 M NaOH
C.100 mL of 0.1 M HCl + 200 mL of 0.1 M $N H_{4} OH$ ✓
D.100 mL of 0.1 M HCl + 100 mL of 0.1 M NaOH

The worked solution is part of a paid pack.

Q30 open Aldehydes, Ketones and Carboxylic Acids · Carboxylic acids: acidity and reactions

The major product of strongly heating phthalic acid (benzene-1,2-dicarboxylic acid) with $N H_{3}$ is:

A.Phthalic acid monoamide (o- $C_{6} H_{4} (COOH) (CON H_{2})$ )
B.Phthalimide (cyclic imide)✓
C.o-Toluic acid
D.o-Phenylenediamine

The worked solution is part of a paid pack.

Q31 open The p-Block Elements · Group 17 and 18: halogens, noble gases

Match the xenon compounds in Column I with their molecular geometry in Column II:

Column I	Column II
(a) $Xe F_{4}$	(i) Pyramidal
(b) $Xe F_{6}$	(ii) Square planar
(c) $XeO F_{4}$	(iii) Distorted octahedral
(d) $Xe O_{3}$	(iv) Square pyramidal

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

The worked solution is part of a paid pack.

Q32 open The d- and f-Block Elements · Potassium dichromate and permanganate

The manganate ( $Mn O_{4}^{2 -}$ ) and permanganate ( $Mn O_{4}^{-}$ ) ions are tetrahedral, due to:

A. $π$ -bonding involving overlap of p-orbitals of oxygen with d-orbitals of manganese✓
B.The absence of any $π$ -bonding
C. $π$ -bonding involving overlap of p-orbitals of oxygen with p-orbitals of manganese
D. $π$ -bonding involving overlap of d-orbitals of oxygen with d-orbitals of manganese

The worked solution is part of a paid pack.

Q33 open The p-Block Elements · Group 13 and 14 elements

Which of the following species is not stable?

A. $[Si F_{6}]^{2 -}$
B. $[GeC l_{6}]^{2 -}$
C. $[Sn (OH)_{6}]^{2 -}$
D. $[SiC l_{6}]^{2 -}$ ✓

The worked solution is part of a paid pack.

Q34 open Electrochemistry · Electrochemical cells and Nernst equation

For a cell involving one electron transfer, $E_{ce l l}^{\circ} = 0.59$ V at 298 K. The equilibrium constant for the cell reaction is: (Given: $\frac{2.303 R T}{F} = 0.059$ V at $T = 298$ K)

A. $1.0 \times 1 0^{2}$
B. $1.0 \times 1 0^{5}$
C. $1.0 \times 1 0^{10}$ ✓
D. $1.0 \times 1 0^{30}$

The worked solution is part of a paid pack.

Q35 open

Which of the following is an amphoteric hydroxide?

A. $Sr (OH)_{2}$
B. $Ca (OH)_{2}$
C. $Mg (OH)_{2}$
D. $Be (OH)_{2}$ ✓

The worked solution is part of a paid pack.

Q36 open

A gas at 350 K and 15 bar has a molar volume 20% smaller than that for an ideal gas under the same conditions. The correct statement about the gas and its compressibility factor ( $Z$ ) is:

A. $Z > 1$ and attractive forces are dominant
B. $Z > 1$ and repulsive forces are dominant
C. $Z < 1$ and attractive forces are dominant✓
D. $Z < 1$ and repulsive forces are dominant

The worked solution is part of a paid pack.

Q37 open

A compound is formed by cation C and anion A. The anions form a hexagonal close-packed (hcp) lattice and the cations occupy 75% of the octahedral voids. The formula of the compound is: