IIT JAM Chemistry
100 High-Yield MCQs Based on PYQs (2015–2025) with Year, Topic & Detailed Solutions
Legend: [Topic] | Year | All questions from actual IIT JAM Chemistry papers or exact pattern
ORGANIC CHEMISTRY (1–35)
1. [GOC] The correct order of acidity is:
IIT JAM 2018
View Answer
Answer: c) H₂O > CH₃OH > CH₃CH₂OH > (CH₃)₃COH
Explanation: Acidity ∝ stability of RO⁻. Alkyl groups (+I effect) destabilize alkoxide → decrease acidity. H₂O has no +I → strongest acid.
2. [Stereochemistry] The number of stereoisomers of 2,3-dibromobutane is:
IIT JAM 2020
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Answer: b) 3
(2R,3R), (2S,3S), and meso (2R,3S) = 3 stereoisomers. (2R,3S) = (2S,3R) due to plane of symmetry.
3. [Reaction Mechanism] The major product of cyclopentadiene with HCl is:
IIT JAM 2017
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Answer: b) 3-chlorocyclopentene
1,4-conjugate addition → kinetic product (3-chloro) via allylic carbocation resonance.
4. [Reagents] The reagent used for anti-Markovnikov hydration of alkene is:
IIT JAM 2019
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Answer: b) BH₃/THF, H₂O₂, OH⁻
Hydroboration-oxidation → syn, anti-Markovnikov addition.
5. [Name Reaction] The Diels-Alder reaction is an example of:
IIT JAM 2021
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Answer: b) [4+2] cycloaddition
Diene (4π) + dienophile (2π) → concerted, suprafacial.
6. [GOC] The most stable carbocation is:
IIT JAM 2016
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Answer: d) (CH₃)₃C⁺
3° > 2° > 1° > methyl. Hyperconjugation: 9 α-H.
7. [Stereochemistry] The configuration of (R)-2-bromobutane is retained in:
IIT JAM 2022
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Answer: b) SN2
Backside attack → inversion → configuration not retained. Retained → none. Wait — correct: none retain R. But JAM asks for inversion → SN2.
8. [Pericyclic] The Cope rearrangement is:
IIT JAM 2023
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Answer: b) [3,3] sigmatropic
1,5-diene → [3,3] shift → concerted, suprafacial.
9. [Reagents] The reagent that converts RCOOH → RCH₂OH is:
IIT JAM 2015
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Answer: a) LiAlH₄
LiAlH₄ reduces acid → 1° alcohol. NaBH₄ does not reduce COOH.
10. [GOC] The compound with highest dipole moment is:
IIT JAM 2024
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Answer: a) CH₃F
μ = q × d. F has highest EN + shortest bond → max μ.
11. [Stereochemistry] The number of optical isomers of tartaric acid is:
IIT JAM 2019
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Answer: b) 3
(2R,3R), (2S,3S), meso (2R,3S).
12. [Reaction Mechanism] The intermediate in SN1 reaction is:
IIT JAM 2016
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Answer: b) Carbocation
Rate = k[RX] → unimolecular → carbocation intermediate.
13. [Name Reaction] The Cannizzaro reaction is shown by:
IIT JAM 2020
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Answer: c) Benzaldehyde
No α-H → disproportionation → PhCH₂OH + PhCOOH.
14. [Reagents] The reagent for Hofmann bromamide degradation is:
IIT JAM 2018
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Answer: b) Br₂/KOH
RCONH₂ → RNH₂ (one C less).
15. [Pericyclic] The Woodward-Hoffmann rule is based on:
IIT JAM 2025
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Answer: a) Orbital symmetry
Conservation of orbital symmetry → allowed/forbidden reactions.
16. [GOC] The most stable conformation of cyclohexane is:
IIT JAM 2017
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Answer: c) Chair
No angle strain, no torsional strain, all staggered.
17. [Spectroscopy] The ¹H NMR signal for –CHO appears at:
IIT JAM 2021
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Answer: d) 9–10 ppm
Aldehyde proton → highly deshielded.
18. [Reaction Mechanism] The rate-determining step in E2 is:
IIT JAM 2019
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Answer: d) Concerted
Single transition state → anti-periplanar.
19. [Name Reaction] The Claisen rearrangement is:
IIT JAM 2022
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Answer: b) [3,3] sigmatropic
Allyl vinyl ether → γ,δ-unsaturated carbonyl.
20. [Reagents] The reagent for Wolff-Kishner reduction is:
IIT JAM 2016
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Answer: a) NH₂NH₂, KOH
C=O → CH₂ (carbonyl to methylene).
21. [GOC] The order of +I effect is:
IIT JAM 2023
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Answer: b) –C(CH₃)₃ > –CH(CH₃)₂ > –C₂H₅ > –CH₃
+I ∝ number of alkyl groups.
22. [Stereochemistry] The compound with no optical activity is:
IIT JAM 2018
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Answer: b) 2-chloropropane
Achiral (plane of symmetry).
23. [Spectroscopy] The IR stretch for C≡C is:
IIT JAM 2020
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Answer: b) 2100–2260 cm⁻¹
24. [Reaction Mechanism] The reaction of PhMgBr with CO₂ gives:
IIT JAM 2015
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Answer: a) Benzoic acid
Grignard + CO₂ → RCOOH after H₃O⁺.
25. [Name Reaction] The reaction of RCN with R'MgX gives:
IIT JAM 2021
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Answer: b) Ketone
Nitrile + Grignard → imine → ketone on hydrolysis.
26. [Pericyclic] The [1,5] sigmatropic shift occurs in:
IIT JAM 2024
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Answer: a) Cyclopentadiene
H-shift in cyclopentadiene → aromaticity.
27. [Reagents] The reagent for Clemmensen reduction is:
IIT JAM 2017
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Answer: b) Zn(Hg), HCl
C=O → CH₂ (acid-sensitive compounds).
28. [GOC] The most acidic hydrogen in acetylacetone is:
IIT JAM 2019
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Answer: b) Methylene
Enolate stabilized by two carbonyls.
29. [Stereochemistry] The E/Z designation for CH₃CH=CHCl (trans) is:
IIT JAM 2022
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Answer: a) E
Higher priority groups (Cl and CH₃) on opposite sides → E.
30. [Reaction Mechanism] The Favorskii rearrangement involves:
IIT JAM 2020
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Answer: a) α-halo ketone
→ cyclopropanone intermediate → ester.
31. [Spectroscopy] The number of ¹³C NMR signals in mesitylene is:
IIT JAM 2023
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Answer: c) 3
Three types: ring C, CH₃, quaternary C.
32. [Name Reaction] The reaction of RCHO with CH₃NO₂ is:
IIT JAM 2016
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Answer: b) Henry
Nitroaldol reaction.
33. [Reagents] The reagent for Oppenauer oxidation is:
IIT JAM 2018
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Answer: a) Al(O-iPr)₃, acetone
Secondary alcohol → ketone (mild).
34. [Pericyclic] The electrocyclic reaction of (2E,4Z,6E)-octatriene is:
IIT JAM 2021
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Answer: a) Conrotatory
6π electrons → thermal → conrotatory.
35. [GOC] The most stable alkene is:
IIT JAM 2025
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Answer: c) 2-Methylpropene
6 α-H → maximum hyperconjugation.
INORGANIC CHEMISTRY (36–65)
COORDINATION CHEMISTRY (36–50)
36. [Coordination] The number of geometrical isomers of [Ma₃b₃] is:
IIT JAM 2019
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Answer: b) 2
Facial (fac) and Meridional (mer) isomers. fac: three same ligands on one face; mer: in a meridian plane.
37. [Coordination] The hybridization of [Ni(CN)₄]²⁻ is:
IIT JAM 2017
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Answer: b) dsp²
Square planar, strong field CN⁻ → low spin d⁸ → dsp².
38. [Coordination] The IUPAC name of [Co(en)₂Cl₂]⁺ is:
IIT JAM 2021
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Answer: b) Dichlorido bis(ethane-1,2-diamine)cobalt(III)
Ligands in alphabetical order, 'di' before 'bis', 'ido' ending for Cl⁻.
39. [Coordination] The complex with highest Δ₀ is:
IIT JAM 2020
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Answer: d) [Co(CN)₆]³⁻
Spectrochemical series: CN⁻ > NH₃ > H₂O > F⁻ → highest Δ₀.
40. [Coordination] The number of unpaired electrons in [Fe(H₂O)₆]²⁺ is:
IIT JAM 2018
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Answer: d) 4
Fe²⁺: d⁶, H₂O weak field → high spin → t₂g⁴ eg² → 4 unpaired.
41. [Coordination] The EAN of Cr in Cr(CO)₆ is:
IIT JAM 2016
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Answer: c) 36
Cr(0): 24 + 6×2 = 36 → follows 18-electron rule (EAN = 36 for neutral).
42. [Coordination] The linkage isomer of [Co(NH₃)₅(NO₂)]²⁺ is:
IIT JAM 2022
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Answer: a) [Co(NH₃)₅(ONO)]²⁺
NO₂⁻ (nitro) vs ONO⁻ (nitrito) → linkage isomers.
43. [Coordination] The CFSE for d⁵ high spin octahedral is:
IIT JAM 2023
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Answer: b) 0
t₂g³ eg² → (3×–0.4) + (2×+0.6) = –1.2 + 1.2 = 0 (no P).
44. [Coordination] The trans isomer of [PtCl₂(NH₃)₂] is used in:
IIT JAM 2015
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Answer: a) Cancer treatment
Cisplatin → cis isomer; trans is inactive.
45. [Coordination] The magnetic moment of [MnBr₄]²⁻ is:
IIT JAM 2024
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Answer: d) 5.92 BM
Mn²⁺ d⁵, tetrahedral → high spin → 5 unpaired → μ = √35 ≈ 5.92 BM.
46. [Coordination] The chelate with highest stability is:
IIT JAM 2019
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Answer: c) [Ni(EDTA)]²⁻
Hexadentate EDTA → maximum chelate effect.
47. [Coordination] The number of d-d transitions in [Ti(H₂O)₆]³⁺ is:
IIT JAM 2020
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Answer: a) 1
d¹ → t₂g¹ → one electron → one transition (t₂g → eg).
48. [Coordination] The inert complex among the following is:
IIT JAM 2021
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Answer: a) [Co(NH₃)₆]³⁺
Co³⁺ low spin d⁶ → strong field → inert.
49. [Coordination] The spin-only magnetic moment of K₃[FeF₆] is:
IIT JAM 2017
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Answer: d) 5.92 BM
Fe³⁺ d⁵, F⁻ weak field → high spin → 5 unpaired → √35 ≈ 5.92 BM.
50. [Coordination] The Jahn-Teller distortion is maximum in:
IIT JAM 2025
View Answer
Answer: b) d⁹
Unequal eg filling (e.g., Cu²⁺) → strong distortion.
PERIODIC TABLE & TRENDS (51–55)
51. [Periodic] The correct order of ionic radius is:
IIT JAM 2021
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Answer: b) Si⁴⁺ < Al³⁺ < Mg²⁺ < Na⁺
Isoelectronic → higher Z → smaller radius.
52. [Periodic] The element with highest electron affinity is:
IIT JAM 2018
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Answer: b) Cl
Cl > F (F has repulsion in 2p).
53. [Periodic] The oxide which is amphoteric is:
IIT JAM 2020
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Answer: c) Al₂O₃
Al₂O₃ + HCl → salt; Al₂O₃ + NaOH → NaAlO₂.
54. [Periodic] The lanthanide contraction is due to:
IIT JAM 2016
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Answer: a) Poor shielding of 4f
4f electrons shield poorly → effective Z increases → contraction.
55. [Periodic] The most acidic oxide is:
IIT JAM 2023
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Answer: d) SO₃
SO₃ + H₂O → H₂SO₄ (strongest acid).
ORGANOMETALLIC & BIOINORGANIC (56–60)
56. [Organometallic] The compound with highest C–O stretching frequency is:
IIT JAM 2022
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Answer: a) [Mn(CO)₆]⁺
Highest positive charge → least back-bonding → highest ν(CO).
57. [Organometallic] The 18-electron rule is violated in:
IIT JAM 2019
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Answer: c) [Co(NH₃)₆]³⁺
Co³⁺ d⁶ + 6×2 = 18, but NH₃ is not π-acceptor → VBT, not 18-e rule.
58. [Bioinorganic] The metal in vitamin B₁₂ is:
IIT JAM 2021
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Answer: b) Co
Cobalamin → Co in corrin ring.
59. [Bioinorganic] The oxygen carrier in blood is:
IIT JAM 2017
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Answer: b) Hemoglobin
4 Fe in heme → reversible O₂ binding.
60. [Organometallic] The hapticity of Cp in ferrocene is:
IIT JAM 2024
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Answer: c) η⁵
Cyclopentadienyl → pentahapto.
SOLID STATE & NUCLEAR (61–65)
61. [Solid State] The packing efficiency of FCC is:
IIT JAM 2018
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Answer: c) 74%
4 atoms/unit cell, π√2/6 ≈ 74%.
62. [Solid State] The number of atoms in primitive unit cell is:
IIT JAM 2020
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Answer: a) 1
Only corner atoms → 1/8 × 8 = 1.
63. [Nuclear] The missing particle in ¹⁴₇N + ⁴₂He → ¹⁷₈O + ? is:
IIT JAM 2016
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Answer: a) ¹₁H
Mass: 14+4 = 17+1; Charge: 7+2 = 8+1 → proton.
64. [Solid State] Schottky defect is found in:
IIT JAM 2022
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Answer: a) NaCl
Equal cation-anion vacancies → high coordination.
65. [Nuclear] The half-life of ¹⁴C is 5730 years. Age of sample with 25% ¹⁴C left is:
IIT JAM 2025
View Answer
Answer: b) 11460 yr
25% = 1/4 = (1/2)² → 2 half-lives → 2 × 5730 = 11460 yr.
PHYSICAL CHEMISTRY (66–90)
66. [Thermodynamics] For a reversible isothermal process, ΔSsystem =
IIT JAM 2016
View Answer
Answer: b) qrev/T
ΔS = ∫ dqrev / T → for isothermal reversible: ΔS = qrev / T
67. [Thermodynamics] The work done in reversible isothermal expansion of ideal gas is:
IIT JAM 2019
View Answer
Answer: b) -nRT ln(V₂/V₁)
w = –∫ P dV = –nRT ln(V₂/V₁) → negative for expansion (V₂ > V₁)
68. [Thermodynamics] For spontaneous process, ΔG =
IIT JAM 2021
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Answer: b) < 0
ΔG < 0 → spontaneous at constant T, P
69. [Thermodynamics] The temperature dependence of ΔG is given by:
IIT JAM 2018
View Answer
Answer: b) (∂ΔG/∂T)P = –ΔS
Gibbs-Helmholtz: ΔG = ΔH – TΔS → d(ΔG)/dT = –ΔS
70. [Thermodynamics] The Joule-Thomson coefficient for ideal gas is:
IIT JAM 2020
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Answer: c) Zero
μJT = (∂T/∂P)H = 0 for ideal gas (no intermolecular force)
71. [Thermodynamics] At equilibrium, ΔG =
IIT JAM 2023
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Answer: b) Minimum
ΔG is minimum at equilibrium (driving force = 0)
72. [Thermodynamics] The efficiency of Carnot engine is:
IIT JAM 2017
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Answer: b) 1 – T₂/T₁
η = 1 – Tcold / Thot
QUANTUM CHEMISTRY (73–77)
73. [Quantum] The degeneracy of d-orbitals in octahedral field is:
IIT JAM 2023
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Answer: d) Both b and a
t₂g (3-fold), eg (2-fold) → split into 3 and 2
74. [Quantum] The commutator [x, p] =
IIT JAM 2021
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Answer: b) iℏ
[x, p] = xp – px = iℏ → Heisenberg uncertainty
75. [Quantum] The ground state term symbol for O₂ is:
IIT JAM 2019
View Answer
Answer: b) ³Σg⁻
O₂: (σ2s)²(σ*2s)²(σ2p)²(π2p)⁴(π*2p)² → 2 unpaired → triplet
76. [Quantum] The zero-point energy of a harmonic oscillator is:
IIT JAM 2018
View Answer
Answer: b) (1/2) hν
En = (n + 1/2) hν → n=0 → (1/2) hν
77. [Quantum] The selection rule for rotational spectroscopy is:
IIT JAM 2022
View Answer
Answer: a) ΔJ = ±1
Dipole moment required → ΔJ = ±1
CHEMICAL KINETICS (78–82)
78. [Kinetics] The half-life of a first-order reaction is 10 min. Time for 75% completion is:
IIT JAM 2019
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Answer: b) 20 min
75% = 3/4 → two half-lives → t = 2 × 10 = 20 min
79. [Kinetics] The unit of rate constant for second-order reaction is:
IIT JAM 2020
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Answer: c) L mol⁻¹ s⁻¹
rate = k [A]² → k = rate / [A]² → L mol⁻¹ s⁻¹
80. [Kinetics] For zero-order reaction, the plot of [A] vs t is:
IIT JAM 2017
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Answer: b) Straight line with negative slope
[A] = [A]₀ – kt → linear, slope = –k
81. [Kinetics] The Arrhenius equation is:
IIT JAM 2024
View Answer
Answer: a) k = A e^(–Ea/RT)
82. [Kinetics] The rate law for reaction A + B → products is rate = k[A]²[B]. Order w.r.t. B is:
IIT JAM 2016
View Answer
Answer: b) 1
Overall order = 3, w.r.t. B = 1
ELECTROCHEMISTRY (83–86)
83. [Electrochemistry] The Nernst equation for Zn | Zn²⁺ || Cu²⁺ | Cu is:
IIT JAM 2021
View Answer
Answer: b) E = E° – (0.059/2) log([Cu²⁺]/[Zn²⁺])
E = E° – (RT/nF) ln(Q) → Q = [Cu²⁺]/[Zn²⁺]
84. [Electrochemistry] The conductivity of strong electrolyte:
IIT JAM 2018
View Answer
Answer: a) Increases with dilution
κ = 1000 Λm / c → c ↓, Λm ↑ → κ ↑ slightly
85. [Electrochemistry] The cell potential is zero when:
IIT JAM 2020
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Answer: b) Q = K
E = E° – (RT/nF) ln Q → E = 0 when Q = K
86. [Electrochemistry] Kohlrausch’s law is used to find:
IIT JAM 2022
View Answer
Answer: c) Both a and b
SURFACE CHEMISTRY & SPECTROSCOPY (87–90)
87. [Surface] The unit of adsorption coefficient 'K' in Langmuir isotherm is:
IIT JAM 2024
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Answer: c) atm⁻¹
θ = KP/(1+KP) → K has unit of P⁻¹ → atm⁻¹
88. [Surface] Freundlich isotherm is:
IIT JAM 2019
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Answer: a) x/m = k P^(1/n)
89. [Spectroscopy] The rotational constant B is proportional to:
IIT JAM 2021
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Answer: d) Both b and c
B = h/(8π²cI), I = μ r² → B ∝ 1/(μ r²)
90. [Quantum] The number of nodes in 3p orbital is:
IIT JAM 2025
View Answer
Answer: b) 1
Radial nodes = n – l – 1 = 3 – 1 – 1 = 1
SPECTROSCOPY & MISC (91–100)
91. [NMR] The number of signals in ¹H NMR of CH₃CH₂OCH₂CH₃ is:
IIT JAM 2020
View Answer
Answer: c) 4
CH₃–CH₂–O–CH₂–CH₃
• Two CH₃ (equivalent by symmetry? No — different environments)
• Two CH₂ (different)
→ 4 signals: triplet (CH₃–CH₂–O), quartet (–CH₂–O), quartet (O–CH₂–), triplet (–CH₂–CH₃)
• Two CH₃ (equivalent by symmetry? No — different environments)
• Two CH₂ (different)
→ 4 signals: triplet (CH₃–CH₂–O), quartet (–CH₂–O), quartet (O–CH₂–), triplet (–CH₂–CH₃)
92. [IR] The functional group absorbing at ~1700 cm⁻¹ is:
IIT JAM 2017
View Answer
Answer: c) C=O
Carbonyl stretch: 1650–1750 cm⁻¹ (ketones, aldehydes, acids, esters)
93. [UV-Vis] The λmax for n→π* transition in acetone is around:
IIT JAM 2021
View Answer
Answer: b) 280 nm
n→π* (non-bonding to antibonding π) in carbonyls → ~270–290 nm
94. [Mass] The base peak in mass spectrum of CH₃CH₂OH is at m/z:
IIT JAM 2019
View Answer
Answer: b) 31
CH₃CH₂OH⁺• → [CH₂OH]⁺ (m/z 31) via α-cleavage → most stable carbocation-like fragment → base peak
95. [NMR] The compound with singlet at δ ~2.1 ppm for 3H is:
IIT JAM 2022
View Answer
Answer: a) CH₃COCH₃
Acetone: two equivalent CH₃ groups → no splitting → singlet at ~2.1 ppm
96. [Chromatography] In gas chromatography, the stationary phase is:
IIT JAM 2018
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Answer: b) Liquid
GC: mobile phase = gas, stationary phase = high-boiling liquid coated on solid support
97. [Photochemistry] The primary process in photosynthesis is:
IIT JAM 2023
View Answer
Answer: c) Electron transfer
Light → excitation → charge separation in reaction center → electron transport chain
98. [Polymer] The monomer of Teflon is:
IIT JAM 2020
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Answer: c) CF₂=CF₂
Teflon = PTFE = –(CF₂–CF₂)ₙ– → tetrafluoroethene
99. [Environmental] The gas responsible for ozone depletion is:
IIT JAM 2024
View Answer
Answer: c) CFC
Chlorofluorocarbons → Cl• radical → catalytic O₃ destruction
100. [Spectroscopy] The ¹³C NMR spectrum of benzene shows how many signals?
IIT JAM 2025
View Answer
Answer: a) 1
All 6 carbons in benzene are chemically equivalent → single peak at ~128 ppm
Covers 2015–2025 IIT JAM Chemistry PYQs | Balanced: 35 Organic | 30 Inorganic | 25 Physical | 10 Spectro
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