| Post Name | SCIENTIFIC OFFICER (CHEMISTRY)-KERALA POLICE SERVICE (FORENSIC SCIENCE LABORATORY) |
|---|---|
| Question Paper Code | 020/2021 |
| Category Code | 027/2020 |
| Date of Test | 28 January 2021 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
A solution of HCl in water is 10.0% HCl by mass. Find the mole fraction of HCl in this solution.
Answer
B. 0.051
2
A cylinder fitted with a frictionless piston contains 2.00 mol of He perfect gas at pressure 1.00 atm and is in a large constant-temperature bath at 500 K. The pressure is reversibly increased to 10.00 atm. Calculate the work done on this process. (R = 8.314 J mol–1 K–1)
Answer
A. 19147 J
3
Which of this statement is incorrect for a fixed amount of a perfect gas?
Answer
B. P dV = nR dT for every infinitesimal process.
4
Which of the following equation relates the chemical potential and the composition of a mixture ?
Answer
D. Gibbs-Duhem
5
The change in entropy for reversible phase change (ΔH = +) at constant temperature and pressure is
Answer
A. Positive
6
Identify the correct Clausius-Clapeyron equation from the following options (Vf and Vi are final and initial specific volumes, respectively):
Answer
C. dP/dT = ΔH/[T(Vf − Vi)]
7
According to A₂(g) ⇌ 2A(ads), the Langmuir adsorption isotherm for the dissociative adsorption (where ads = adsorbed, P is the partial pressure of A₂ and k is the ratio of rate constants for adsorption and desorption) is
Answer
D. θ = √(kP)/(1 + √(kP))
8
The equation ln γ± = −z⁺|z⁻|AIₘ¹ᐟ² is called the Debye-Hückel limiting law (Iₘ = molality-scale ionic strength; γ± = molality-scale mean ionic activity coefficient). Under which condition do the experimental data show that the equation gives the correct limiting behaviour for electrolyte solutions?
Answer
B. Iₘ → 0
9
Calculate the ionic strength Im in a solution that contains 0.0200 mol KCl, 0.0050 mol MgCl2, 0.0020 mol MgSO4 and 100 g H2O.
Answer
C. 0.430 mol.kg–1
10
Read the following statements carefully : (i) The incident electron beam ionizes an atomic core level electron. (ii) The energy released when a higher-energy electron falls back to fill the core level is transferred to a valence electron, which is ejected into the gas phase where it is detected. These processes involving in the principle of
Answer
C. Auger Electron Spectroscopy
11
The concentration of a reactant R varies with time for two different reactions shown in the printed graphs: graph I is a straight-line decrease of [R] versus time, and graph II is a straight-line decrease of ln[R] versus time. The orders of reactions I and II, respectively, are
Answer
D. 0 and 1
12
Which one of the following process is non-spontaneous ?
Answer
C. Freezing of water at 0 °C and 1 atm pressure
13
The standard electrode-potential values for the half-cell reactions Cd²⁺ + 2e⁻ → Cd and Zn²⁺ + 2e⁻ → Zn are −0.40 V and −0.76 V, respectively. Which statement is true?
Answer
B. Zinc is more electropositive than cadmium
14
From the half-cell reactions Mn²⁺ + 2e⁻ → Mn, E° = −1.18 V, and Mn³⁺ + 2e⁻ → Mn²⁺, E° = +1.51 V, determine the standard reduction potential and conclude whether the reaction 3Mn²⁺ → 2Mn³⁺ + Mn is feasible.
Answer
Question Cancelled
15
The point group of CO₂ is D∞h. Which pair of molecules below also has the same point group?
Answer
A. HCCH and XeF₂
16
For 1.00 mol·dm⁻³ KCl(aq) at 25 °C and 1 atm, the conductivity κ is 0.115 Ω⁻¹ cm⁻¹. Calculate its molar conductivity Λₘ in Ω⁻¹ m² mol⁻¹.
Answer
C. 0.0115
17
Pick out the correct answer(s): (i) Addition of a solute at constant T and P to a solution containing solvent A always decreases chemical potential μA. (ii) The vapour pressure of a solution of A and B at temperature T is always less than the vapour pressure of pure A at T.
Answer
B. Only (i)
18
Consider the following statements about the salt bridge : (i) It enhances the rate of the reaction. (ii) It can minimizes the junction potential. (iii) It consists of an electrolyte in a gel. The correct statement/s is/are
Answer
D. Only (ii and iii)
19
The gas-phase reaction 2NO₂Cl → 2NO₂ + Cl₂ has rate law r = k[NO₂Cl]. The rate-determining step consistent with this rate law is
Answer
B. NO₂Cl → NO₂ + Cl
20
Identify the correct product when the depicted cyclohexane bearing adjacent dashed-wedge OH and NH₂ groups and a solid-wedge tert-butyl group is treated with NaNO₂/HCl.
Answer
D. tert-Butyl-substituted cyclohexanone
21
The depicted reaction is elimination of 2-bromo-2-methylbutane with t-BuOK, producing 2-methyl-1-butene and 2-methyl-2-butene. Which statements are correct? (i) E1 reaction. (ii) E2 reaction. (iii) Major product is more substituted alkene. (iv) Major product is less substituted alkene.
Answer
D. Only (ii & iv)
22
One of the space groups for the monoclinic crystal system is P2₁/c. Here, the 2₁ symmetry element corresponds to operation of
Answer
C. Rotation of an axis and translation along that axis
23
Which depicted molecule(s) is/are chiral? Structure (i) is the printed methyl-substituted cyclohexanone with Me on a solid wedge and H on a dashed wedge; structure (ii) is the printed substituted bicyclic O,O-acetal with the indicated solid- and dashed-wedge bonds.
Answer
D. None of them
24
The incorrect feature of R/S-BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) from the following list is
Answer
A. A chiral centre exist
25
Identify the most relevant statement about enantiomers from the following options :
Answer
B. They have identical physical properties but quite different biological effects.
26
Which one of the following rearrangement has given considerable evidence for involving cyclopropanone as reaction intermediate ?
Answer
A. Favorskii
27
Among the four Fischer projections, identify the compound different from the remaining three. Printed projections: (i) top CH₃, bottom Ph, left H, right NH₂; (ii) top NH₂, bottom H, left CH₃, right Ph; (iii) top NH₂, bottom Ph, left CH₃, right H; (iv) top Ph, bottom CH₃, left NH₂, right H.
Answer
B. (ii)
28
What is the stereochemical relationship between the two depicted representations of 1,3-disubstituted cyclohexane: a flat-ring drawing with one solid-wedge and one dashed-wedge substituent, and the corresponding chair drawing with one equatorial-down and one axial-down substituent?
Answer
A. Identical
29
In which medium, benzil-benzilic acid rearrangement occurs ?
Answer
A. Basic
30
Which disconnection (I–IV) is most likely for the depicted bromo-methoxy aryl amide bearing a chiral pyrrolidine substituent? The printed cuts are I at aryl–carbonyl, II at carbonyl–NH, III at NH–chiral-carbon, and IV at pyrrolidine-N–ethyl.
Answer
A. Disconnection I
31
To carry out a retrosynthetic analysis of paracetamol, pick out a reagent (A-D) which is least likely to be useful.
Answer
D. Phenol
32
Which depicted dienes can undergo a Diels-Alder reaction? (i) fused bicyclic diene with one double bond at the ring junction and one in the left ring; (ii) 1-vinylcyclohexene; (iii) cyclohexane bearing two adjacent exocyclic methylene groups; (iv) furan.
Answer
C. Only (iii & iv)
33
Identify the correct product when the depicted 1,3-cyclooctadiene is treated successively with (i) n-BuLi at −78 °C, (ii) warmed to 0 °C, and (iii) H⁺.
Answer
B. Printed fused 5/5 bicyclic alkene with both ring-junction H atoms solid-wedge
34
How many nodes exist in LUMO (Lowest Unoccupied Molecular Orbital) of 1, 3, 5-hexatriene ?
Answer
B. 3
35
Why does the body need sunlight to make provitamin D₂?
Answer
C. For the conversion of ergosterol to provitamin D₂ through electrocyclic reaction
36
Match List I (alkaloid) with List II (skeleton): (i) Nicotine, (ii) Papaverine, (iii) Reserpine, (iv) Quinine; (m) Quinoline, (n) Isoquinoline, (o) Pyrrolidine, (p) Indole.
Answer
D. i-o; ii-n; iii-p; iv-m
37
Of the depicted radicals, which is most stable? (i) cyclohexyl–C•H–CH₃; (ii) a tertiary alkyl radical, CH₃CH₂–C•(CH₃)₂; (iii) an allyl-substituted secondary radical, CH₂=CH–CH₂–C•H–CH₃; (iv) methoxymethyl radical, CH₃O–C•H₂.
Answer
D. (iv)
38
Identify products X and Y in the depicted Robinson annulation sequence: methyl vinyl ketone plus 2-methylcyclohexane-1,3-dione, R₂NH, gives X; p-toluenesulfonic acid converts X to Y.
Answer
C. X: fused decalin diketone with bridgehead CH₃ and bridgehead OH both solid-wedge; Y: left-ring α,β-unsaturated diketone
39
Identify the major product when 2-methylbutane reacts with bromine in the presence of light or heat.
Answer
B. 2-bromo-2-methylbutane
40
Which reaction has a positive Hammett reaction constant, ρ?
Answer
C. Nucleophilic substitution between piperidine and 1-bromo-2-nitrobenzene
41
The first Stokes line and first anti-Stokes line in the rotational Raman spectrum of N₂O are displaced from the Rayleigh line by 2.508 cm⁻¹ on each side. Determine the rotational constant of N₂O.
Answer
D. 0.419 cm⁻¹
42
Pick a pair of molecules that can exhibit both pure rotational and rotational Raman spectra.
Answer
C. NO and HCCD
43
From the list of molecules, which would you expect to have infrared-active vibrations Raman-inactive and vice versa?
Answer
B. Benzene
44
Which compound is most suitable for an infrared spectrum with a broad absorption band at 3000 cm⁻¹, sharper bands on its shoulder at about 3060 cm⁻¹, a strong absorption at about 1700 cm⁻¹, a sharp band at 1600 and 1475 cm⁻¹, and a series of sharp bands between 650 and 800 cm⁻¹?
Answer
C. Benzoic acid
45
Which coordination complex cannot exhibit quadrupole splitting in a ⁵⁷Fe Mössbauer spectrum? (i) K₄[Fe(CN)₆], (ii) [Fe(CO)₅], (iii) Na₃[Fe(CN)₆], (iv) Na₂[Fe(CN)₅NO].
Answer
A. (i)
46
The chemical shift between fat protons and water results in a frequency difference of around 210 Hz at 1.5 T. What would be their frequency difference at 4.5 T ?
Answer
C. 630 Hz
47
¹H NMR shows a singlet while ¹³C NMR exhibits two signals. Based on these data, pick the correct molecule.
Answer
D. Acetone
48
Which molecule gives the most prominent mass-spectrum peak corresponding to a radical cation formed by McLafferty rearrangement? (i) CH₃CH₂COCH₂CH₃; (ii) CH₃CH₂CH₂COCH₃; (iii) (CH₃)₂CHCOCH₃; (iv) (CH₃)₂CHCOCH(CH₃)₂.
Answer
B. (ii)
49
Find the correct characteristic(s) of an n → π* transition: (i) its molar absorptivity is generally less than 2000; (ii) hydrogen-bonding solvents cause pronounced blue shifts; (iii) the absorption band corresponding to n → π* is absent for hydrocarbons.
Answer
D. All of the above (i, ii & iii)
50
The absorption-band maximum for iodine occurs at about 520 nm in CCl₄. Assign the correct transition.
Answer
C. π* → σ*
51
Predict the number of lines in the EPR spectrum of dimethyl nitroxide radical (CH₃)₂NO, assuming the lines do not overlap (I = 1 for ¹⁴N; I = 1/2 for ¹H).
Answer
A. 21
52
Which species is EPR silent? (i) [S₃]⁻, (ii) [S₆]²⁻, (iii) [SO₂]⁻, (iv) [S₄]⁻.
Answer
B. (ii)
53
Consider statements about electronic spectra of octahedral high-spin complexes: (i) Co³⁺ can usually exhibit three absorption peaks; (ii) Cr³⁺ can display a maximum of one absorption peak; (iii) Mn²⁺ has a low molar extinction coefficient (~10⁻² L mol⁻¹ cm⁻¹). The correct statement(s) is/are
Answer
D. Only (iii)
54
Arrange the depicted compounds in decreasing order of pKₐ (Kₐ = acid dissociation constant): (i) ethanol, (ii) 2-butanone, (iii) 2,4-pentanedione.
Answer
A. ii > i > iii
55
Using the Woodward-Fieser rule, arrange the three depicted fused bicyclic conjugated-diene systems in increasing order of λmax: (i) an ethoxy-substituted heteroannular diene, (ii) a homoannular diene, (iii) an unsubstituted heteroannular diene.
Answer
B. iii < i < ii
56
An analysis gives 26.97 g compared with the accepted value 27.06 g. The absolute error (g) and relative error (%) are
Answer
D. 0.09 and 0.33
57
In HPLC, column resolution is Rₛ = 2(tᵣB − tᵣA)/(Wₐ + Wᵦ). The terms Wₐ and Wᵦ describe
Answer
C. Base width of analytes A and B
58
Which one of the statement is not relevant towards the application of GC-MS ?
Answer
D. Provides more authentic qualitative information than most of the spectroscopic methods.
59
The strengths of non-covalent interactions (i) ion-ion, (ii) ion-dipole and (iii) dipole-dipole follow the order
Answer
C. i > ii > iii
60
Consider statements about hydrogen bonding: (i) high degree of directionality; (ii) a special kind of dipole-dipole interaction; (iii) HF₂⁻ is linear with H between the two F atoms, [F···H···F]⁻, involving a strong hydrogen bond. The correct statements are
Answer
D. All of the above (i, ii & iii)
61
Identify a complex that does not obey the 18-electron rule.
Answer
A. Co₆(CO)₁₆
62
Match List I (organometallic complex) with List II (structure): (i) [Cp₃Ni₂]⁺, (ii) vapour state of CpIn, (iii) solid state of CpIn, (iv) Cp₂ReH; (m) open-faced sandwiches, (n) tilted rings, (o) polymer, (p) triple deckers.
Answer
A. i-p; ii-m; iii-o; iv-n
63
Zeise’s salt [Pt(C₂H₄)Cl₃]⁻ shows that ethylene occupies the fourth coordination site of the square-planar complex. Identify the correct representation of π-coordination of ethylene with platinum.
Answer
C. Side-on C=C with an arrow from C=C toward Pt; ethylene carbons shown pyramidalized in the opposite orientation to A
64
Match List I (process) with List II (catalyst): (i) Wilkinson catalyst, (ii) Oxo process, (iii) Monsanto acetic acid process, (iv) Wacker process; (m) [Rh(CO)₂I₂]⁻, (n) [PdCl₄]²⁻, (o) Co₂(CO)₈, (p) [(Ph₃P)₃RhCl].
Answer
D. i-p; ii-o; iii-m; iv-n
65
Which characterization technique would be useful to confirm hydride functionality in H₂Fe(CO)₄?
Answer
C. ¹H NMR
66
Identify the second nuclide formed in the fission reaction ²³⁵₉₂U + ¹₀n → ¹⁰³₄₂Mo + 2·¹₀n + ?
Answer
A. ¹³¹₅₀Sn
67
Talc is a kind of silicate mineral, which can be simply defined as
Answer
B. Magnesium analogue of pyrophyllite
68
Complete the depicted reactions of diborane, B₂H₆: reaction with 2H₃N: gives X, while reaction with 2Et₃N: gives Y.
Answer
A. X = [BH₂(NH₃)₂]BH₄; Y = H₃BNEt₃
69
How many π electrons are present in the trisulfur trinitride anion [S₃N₃]⁻?
Answer
A. 10
70
The number of P–P bonds present in a molecule of P₄S₉ is
Answer
B. 0
71
Match List I (enzymes/coenzymes) with List II (metal ions): (i) Vitamin B₁₂, (ii) Carbonic Anhydrase, (iii) Catechol oxidase, (iv) Xanthine oxidase; (m) Molybdenum, (n) Zinc, (o) Cobalt, (p) Copper.
Answer
D. i-o; ii-n; iii-p; iv-m
72
Match List I (types of nitrides) with List II (examples): (i) ionic nitrides, (ii) covalent nitrides, (iii) metallic nitrides; (m) KNO₂, (n) W₂N, (o) As₄N₄, (p) Na₃N.
Answer
A. i-p; ii-o; iii-n
73
The term symbol for the ground state of carbon is ³P₀. Here the value ‘0’ describes
Answer
B. Total angular momentum
74
Statement: In inorganic chemistry, one analogue of benzene is borazine. This is a misnomer because the chemical properties of borazine and benzene are quite different. Reason: Due to the electronegativity difference between boron and nitrogen, more electron density is localized on the boron atom, weakening π-bonding in the ring. Pick a suitable answer.
Answer
C. Statement is acceptable but the reason needs correction
75
Arrange the molecules in decreasing order of infrared P=O stretching frequency: F₃PO, Cl₃PO, Br₃PO, ClF₂PO.
Answer
C. F₃PO > ClF₂PO > Cl₃PO > Br₃PO
76
Predict the product of the square-planar substitution reaction [PtCl(NO₂)(NH₃)(CH₃)]⁻ + Cl⁻ → ? (printed arrangement: NH₃ trans to CH₃; Cl trans to NO₂).
Answer
D. [PtCl₂(NO₂)(CH₃)]²⁻ (NH₃ replaced by Cl)
77
Among the following complexes, which has the highest rate of water exchange: [Na(OH₂)₆]⁺, [Cr(OH₂)₆]³⁺, [Al(OH₂)₆]³⁺, [Mg(OH₂)₆]²⁺?
Answer
A. [Na(OH₂)₆]⁺
78
A redox reaction between a Co³⁺ complex and [Cr(OH₂)₆]²⁺ usually proceeds through an inner-sphere mechanism. Pick the correct rate-constant order for reaction of [Cr(OH₂)₆]²⁺ with [Co(NH₃)₆]³⁺, [Co(NH₃)₅Cl]²⁺ and [Co(NH₃)₅I]²⁺.
Answer
B. [Co(NH₃)₆]³⁺ < [Co(NH₃)₅Cl]²⁺ < [Co(NH₃)₅I]²⁺
79
An iron rod is parallel to a magnetic field of intensity 1000 A/m. Magnetic flux through the rod is 3 × 10⁻⁴ Wb and its cross-sectional area is 3 cm². The magnetic permeability in Wb A⁻¹ m⁻¹ is
Answer
C. 10⁻³
80
A new allotrope of carbon was discovered by Przemyslaw Gawel, Leo Gross and Harry L. Anderson and published in Science (2019, Vol. 365, Issue 6459, pp. 1299–1301). Pick that finding.
Answer
A. sp-hybridized cyclo[18]carbon
81
What is the dimension of the normalized wave function representing a particle in a one-dimensional box of length l?
Answer
B. l⁻¹ᐟ²
82
According to Dulong and Petit law, the heat capacity at constant volume of monatomic solids is
Answer
B. 3R
83
Which function is an odd function?
Answer
C. (2/l) sin(nπx/l)
84
What is the expectation value of the position operator for the ground-state wave function of a simple harmonic oscillator?
Answer
A. 0
85
Calculate the degeneracy of the energy level 14h²/(8ma²) for a particle in a three-dimensional cubic box of length a.
Answer
C. 6
86
The partition function of a two-level system with a non-degenerate state at energy 0 and an upper doubly degenerate state at energy ε is
Answer
C. q = 1 + 2e^(−βε)
87
If N, V, E, T and μ represent composition, volume, energy, temperature and chemical potential of a thermodynamic system, a canonical ensemble has
Answer
C. N, V, T are common
88
What are the relative populations of the states of a two-level system when the temperature is infinite ?
Answer
C. 1.0
89
What is the residual entropy of carbon monoxide?
Answer
B. R ln(2)
90
How many significant figures do the numbers 0.0523 and 900.0 have, respectively?
Answer
D. 3 and 4
91
Identify a pair of noble-gas fluorides able to convert metallic mercury to HgF₂.
Answer
B. KrF₂ and XeF₆
92
[TiCl₆]³⁻ shows slight compression in Ti–Cl bond length due to the Jahn-Teller effect. Two absorption peaks arise because of transition from
Answer
A. Ground state (²B₂g) to excited states (²B₁g and ²A₁g)
93
1,2-Dichloroethylene has two geometrical isomers. Choose the correct option about their symmetry.
Answer
D. One isomer has a σv plane and the other has a σh plane
94
If all of the vertices of the deltahedron are occupied, the structure is called a closo. Identify a closo structure of boron hydrides from the given below options.
Answer
C. Heptaborane(9)
95
The major products X and Y formed when trans-2-butene reacts with OsO₄ and X is then hydrolysed with H₂O are
Answer
A. X: cyclic osmate ester with one CH₃ solid-wedge and one dashed-wedge; Y: vicinal diol with one CH₃ solid-wedge and one dashed-wedge
96
How many inorganic sulfur present in bacterial rubredoxin ?
Answer
C. 0
97
If all the lattice points of an hcp structure are occupied by uniform hard spheres that touch each other, the % of volume unoccupied is
Answer
D. 26
98
Consider the following statements about liquid crystals : (i) Isotropic (ii) Flow like liquids but have much of the long-range order of solids (iii) The molecules can move about, and the intermolecular spacings are irregular. The correct statement is/are
Answer
B. Only (ii & iii)
99
Read the following statements, then choose the best answers from the given options : (i) Each lattice point in a crystal has the same environment. (ii) No atom need lie at a lattice point. (iii) The basis must have the same stoichiometric composition as the entire crystal.
Answer
D. All of the above (i, ii and iii)
100
Which class of dielectric material exhibits a hysteresis loop of polarization versus electric field?
Answer
D. Ferroelectrics
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