Laboratory Assistant | Kerala PSC QBank

1. Wave number of the line in the visible region of hydrogen spectrum is

$\overline{V}=3R/4$

$\overline{V}=5R/36$

$\overline{V}=7R/144$

$\overline{V}=3R/16$

2. Which of the following set of quantum numbers is possible for the valence electron of sodium atom?

$n=3, l=0, m=0, s=0$

$n=3, l=1, m=1, s=-1/2$

$n=3, l=0, m=0, s=+1/2$

None of the above

3. Correct order of the first ionisation energies of the following elements

$Li<Be<B<C<N$

$Li>Be>B>C>N$

$Li<B<C<Be<N$

$Li<B<Be<C<N$

4. Bridge bond in diborane is a

3c-2e bond

3c-3e bond

2c-2e bond

2c-3e bond

5. Hybridisation and structure of $BrF_3$ compound is

$sp^2$ , Trigonal planar

$sp^3$ , Pyramidal

$sp^3d$ , T-shaped

$sp^3$ , Distorted tetrahedral

6. Helium does not form quinol clathrate because

Helium is too large to fit in quinol

Helium is too small to fit in quinol

Helium reacts with quinol

Helium does not react with quinol

7. Fajan's rules summarize the factors favouring

lonisation energy and bonding

Electron affinity and bonding

lonisation energy and covalency

Polarization and covalency

8. Bond order of the following molecules is in the order

$O_2 > O_2^+ > O_2^- > N_2$

$N_2 > O_2 > O_2^+ > O_2^-$

$O_2 > N_2 > O_2^+ > O_2^-$

$N_2 > O_2^+ > O_2 > O_2^-$

9. Which of the following statements are correct about hydrogen bonding ? i. $H_2O$ is liquid. ii. Density of ice is greater than that of water. iii. o-nitrophenol is more volatile.

i and ii

ii and iii

i and iii

i, ii and iii

10. F-centres are produced in

Schottky defect

Frenkel defect

Metal excess defect

Metal deficiency defect

11. Identify the correct statement.

EDTA is a bi-dentate ligand.

Ethylenediamine is a mono-dentate ligand.

EDTA is a hexa-dentate ligand.

Oxalate is a mono-dentate ligand.

12. The number of geometrical isomers possible for $[Co(NH_3)_3(NO_2)_3]$ is

3

2

4

0

13. Which of the following electronic configuration exhibits Jahn-Teller distortion in an $ML_6$ complex? (M refers to metal and L refers to ligand)

$d^3$

$d^6$ (low spin)

$d^7$

$d^5$ (high spin)

14. What are the spin only magnetic moments of $Mn^{2+}$ ion in high spin and low spin complexes, respectively ?

5.92 BM and 1.73 BM

3.88 BM and 1.73 BM

2.83 BM and 5.92 BM

0 BM and 1.73 BM

15. Which of the following is an ore of lead ?

Pyrolusite

Sphalerite

Bauxite

Galena

16. Which electrolyte is used in the electrolytic reduction of Aluminium?

Cryolite

Aluminium sulphate

Aluminium nitrate

Aluminium chloride

17. What is the initial step in the Kroll's process?

Chlorination of Titanium ore

Reduction of Titanium chloride

Distillation of Titanium metal

Purification of Titanium metal

18. The metal ion centre present in Carbonic anhydrase is

Magnesium

Zinc

Copper

Iron

19. In deoxyhaemoglobin, the $Fe^{2+}$ exists in

High spin state and exhibits paramagnetism

Low spin state and exhibits diamagnetism

High spin state and exhibits diamagnetism

Low spin state and exhibits paramagnetism

20. What is the ratio of Sodium to Potassium ions transported by the Sodium - Potassium pump for every ATP breakdown?

1:1

2:1

3:2

4:3

21. Which of the following carbonyls is paramagnetic ?

$Cr(CO)_6$

$Mn(CO)_5$

$Ni(CO)_4$

$Fe(CO)_5$

22. The CO stretching frequency in IR spectroscopy decreases when

Backbonding is strong

Backbonding is weak

CO acts only as a $\sigma$ -donor

The metal is in a high oxidation state

23. Which of the following statements about Wilkinson's catalyst is correct? I. It contains Rhodium in the +1 oxidation state. II. It is used for alkene hydrogenation. III. It works via a mechanism involving oxidative addition and reductive elimination.

Only I

Only II and III

Only I and II

All are correct

24. Which of the following statements is correct about Fischer-Tropsch synthesis ? I. It converts syngas into hydrocarbons. II. It uses cobalt or iron as catalysts. III. It produces acetaldehyde from ethene.

Only I and II

Only II and III

Only III

I, II and III

25. Match the following compounds with their descriptions.


1. Ferrocene	a. Organometallic compound with a sandwich structure
2. Zeise's salt	b. Catalyst for alkene hydrogenation
3. Wilkinson's catalyst	c. Tetrameric structure with alkyl bridges
4. Methyl lithium	d. Organometallic compound of platinum with ethylene

1-c, 2-b, 3-d, 4-a

1-a, 2-d, 3-b, 4-c

1-b, 2-d, 3-c, 4-a

1-d, 2-a, 3-c, 4-b

26. Which of the following statements is correct about the Wacker process? I. The process converts ethylene to acetaldehyde. II. Palladium (II) chloride is reduced to metallic palladium in the reaction. III. Copper (II) chloride regenerates the palladium (II) catalyst.

Only I and II

Only II and III

Only I and III

All are correct

27. Which of the following statements is false regarding Ziegler-Natta polymerization ? I. It is used for producing highly branched polymers. II. It involves coordination-insertion polymerization. III. Tetraethylaluminium serves as a co-catalyst.

Only I

Only II

Only I and II

Only III

28. Which of the following ion is identified using the Chromyl chloride test?

Potassium

Barium

Lead

Chloride

29. In Thermo Gravimetric Analysis (TGA), what does a weight loss plateau indicate ?

Sample decomposition

Sample stability

Water evaporation

Instrument error

30. What is the pKa value of a weak acid if its Ka value is $2.0 \times 10^{-4}$ ? (log 2 = 0.30)

3.70

4.30

2.30

0.30

31. Which of the following reagents is used to separate Group III cations?

NaOH

$H_2S$ in basic medium

$NH_4Cl + NH_3$

HCl

32. Match the following flame colour with their descriptions.


1. Apple green	a. Potassium
2. Brick red	b. Barium
3. Violet	c. Strontium
4. Crimson red	d. Calcium

1-a, 2-b, 3-c, 4-d

1-c, 2-a, 3-d, 4-a

1-d, 2-b, 3-a, 4-c

1-b, 2-d, 3-a, 4-c

33. What is the purpose of the Q-test in data analysis ?

Evaluate the spread of data

Detect outliers in a dataset

Determine correlation between variables

Compare two sample means

34. Identify the correct statements regarding complexometric titrations. I. EDTA forms stable complexes with most metal ions. II. The indicator used changes color when it binds to metal ions. III. EDTA titrations are unaffected by pH changes.

Only I

Only I and II

Only I and III

I, II and III

35. Consider a compound $C_8H_{10}O_2$ labelled as compound P, which shows optical activity. Upon reaction with H2/Pd-C, it yields an achiral compound Q with the formula $C_8H_{12}O_2$ . Additionally, when compound P undergoes ozonolysis, it produces two compounds an optically active aldehyde R and an achiral ketone S. Which of the following could represent the structure of compound P?

(R)-2-Methyl-1-phenylprop-2-en-1-ol

(S)-1-(3,4-Dimethylphenyl) ethene

(R)-1-(4-Methylphenyl)prop-2-en-1-ol

(S)-1-Phenylprop-2-en-1-ol

36. The inductive effect in organic compounds is primarily due to

Delocalization of $\pi$ -electrons

Transfer of a lone pair of electrons

Polarization of $\sigma$ -bonds due to electronegativity differences

Interaction of p-orbitals with $\pi$ -bonds

37. Which of the following carbocations is the most stable ?

Methyl carbocation $(CH_3^+)$

Ethyl carbocation $(C_2H_5^+)$

Isopropyl carbocation $((CH_3)_2CH^+)$

Tertiary butyl carbocation $((CH_3)_3C^+)$

38. A compound C with molecular formula $C_5H_{10}O_2$ shows the following spectral data : • IR Spectrum: Strong absorption at 1730 cm-1 and a broad absorption between 2500-3300 cm-1. • UV Spectrum: No significant absorption above 200 nm. • 1H NMR Spectrum: Shows a quartet at 4.1 ppm (2H, J=7.0 Hz), a triplet at 1.3 ppm (3H), and a broad singlet at 11.0 ppm (1H). • 13C NMR Spectrum: Shows four signals, with two of them at 170 ppm and 60 ppm. Based on this data, what is the most likely structure of compound C?

Ethyl acetate $(CH_3COOCH_2CH_3)$

Butanoic acid $(CH_3CH_2CH_2COOH)$

Methyl propenoate $(CH_3CH_2COOCH_3)$

Propionic acid $(CH_3CH_2COOH)$

39. Which type of reaction mechanism is followed in the conversion of tert-butyl chloride $(C_4H_9Cl)$ to tert-butyl alcohol $(C_4H_9OH)$ in the presence of water?

$S_N1$

$S_N2$

$E1$

$E2$

40. The absolute configuration of a chiral centre in a molecule is assigned as R or S based on

The orientation of substituents around a double bond

The clockwise or counterclockwise arrangement of substituents according to Cahn-Ingold-Prelog rules

The presence of optical activity

The D/L configuration of the molecule

41. Which of the following would act as the strongest nucleophile in a protic solvent ?

$NH_3$

$H_2O$

OH-

$CH_3O^-$

42. Which of the following statements correctly describes the Wurtz reaction?

The Wurtz reaction is primarily used to synthesize alcohols from alkyl halides in the presence of zinc.

The reaction is limited to the formation of symmetrical alkanes only, as it does not allow for the formation of mixed products.

The use of sodium metal in the reaction facilitates the coupling of two alkyl halides to form a higher alkane.

The Wurtz reaction proceeds via an $S_N1$ mechanism, resulting in the formation of a free carbocation intermediate.

43. According to Baeyer's strain theory, which of the following statements about cycloalkanes is most accurate regarding their stability and strain ?

Cyclopropane is the most stable cycloalkane due to the absence of angle strain.

Cyclobutane, while having some angle strain, can adopt a non-planar conformation that alleviates some torsional strain.

Cyclohexane is unstable because it has both angle strain and torsional strain in its chair conformation.

Baeyer's strain theory suggests that cycloalkanes with more than six carbons exhibit less strain due to increased angle flexibility.

44. Which of the following statements is true regarding the $E1$ mechanism?

It involves a single concerted step.

It occurs in two steps: formation of a carbocation and then deprotonation.

It is favoured by strong bases.

It produces stereoisomers with complete retention of configuration.

45. In a laboratory synthesis, a primary amine $RNH_2$ is treated with excess bromine and sodium hydroxide to produce an alkene via the Hofmann elimination reaction. Which of the following statements correctly describes the outcome of this reaction?

The reaction proceeds via an $S_N2$ mechanism, resulting in a substitution product before elimination occurs.

The major product is determined by the stability of the formed alkene, favouring the more substituted alkene (Zaitsev's rule).

The reaction results in the formation of a quaternary ammonium salt as an intermediate, which then undergoes dehydrohalogenation.

The reaction produces an alkene and releases nitrogen gas as a byproduct due to the loss of the amine nitrogen.

46. In the hydration of alkenes, if water is added in accordance with Markovnikov's rule, which of the following products is formed from propene $(C_3H_6)$ ?

1-Propanol

2-Propanol

Propan-2-ol

Propan-1-ol

47. In the Diels-Alder reaction, the diene component must be in which conformation for the reaction to occur effectively?

Anti-periplanar

s-trans

s-cis

E-trans

48. Which of the following statements are correct? i. Intramolecular Hydrogen bonding exists in ortho-nitro phenol but not in meta and para-nitro phenols. ii. Due to intermolecular H-bond simple phenols exist as associated molecules with higher boiling point. iii. The boiling point of o-nitrophenol is lower compared to its meta and para isomers.

Only i and ii

Only i and iii

Only ii and iii

i, ii and iii

49. Arrange the following compounds in the increasing order of acidity. a. p-nitrophenol b. m-nitrophenol c. 2,4,6-trinitrophenol d. phenol

$a<c<d<b$

$d<b<c<a$

$d<b<a<c$

$b<a<c<d$

50. Arrange the following amino acids in the decreasing order of their basicity. a. N,N-dimethylaniline b. Aniline c. N-methylaniline

$a>c>b$

$b>c>a$

$b>a>c$

None of the above

51. The amine 'Y' that reacts with p-toluene sulphonyl chloride in the above reaction can be

$(CH_3)_3N$

$CH_3-NH_2$

$(CH_3)_4N^+I^-$

$(CH_3)_2NH$

52. When vapours of secondary alcohols are passed over copper at a very high temperature of $300^{\circ}C$ , the product formed due to dehydrogenation is

Aldehyde

Alkene

Ketone

None of the above

53. Identify the reagent 'Y' in the following conversion : Phenol -> o-hydroxybenzaldehyde + p-hydroxybenzaldehyde

$CHCl_3/Alc. KOH$

$CO_2/Heat$

Conc. $H_2SO_4$

$NaNO_2$ /Conc. $H_2SO_4$

54. Walden inversion process is connected with which of these reactions?

$S_N1$

$S_N2$

$S_Ni$

SNAr

55. Hantzsch synthesis for the preparation of pyridine involves the condensation of $\beta$ -dicarbonyl compound with an

Aldehyde and HCN

Ketone and $H_2SO_4$

Aldehyde and $NH_3$

Ketone and $NH_3$

56. Which among the following statements is false ? a. $S_N2$ process is suppressed in the presence of polar aprotic solvent. b. The reactivity rate of both $S_N1$ and $S_N2$ reactions of alkyl halides is in the order $RI > RBr > RCl > RF$ .

only a

only b

a and b

none of the above

57. Identify the organic synthesis below.

Skraup synthesis of quinoline

Friedlander's synthesis

Knorr quinoline synthesis

Bischler-Napieralski synthesis

58. Among these 3 heterocyclic compounds, which is the correct order of aromaticity ?

Thiophene > Pyrrole > Furan

Pyrrole > Furan > Thiophene

Furan < Pyrrole > Thiophene

Pyrrole > Thiophene > Furan

59. Formaldehyde reacts with the Grignard reagent methyl magnesium iodide - to form

n-propyl alcohol

Ethyl alcohol

Isopropyl alcohol

Tert-butyl alcohol

60. Predict the product of the following reaction. Cyclohexanone + Isobutylamine -> ?

Cyclohexylideneisobutylamine

N-isobutylcyclohexanamine

1-isobutylaminocyclohexan-1-ol

N-cyclohexylisobutylamine

61. Which of the following product is formed when cyclohexanone undergoes Baeyer-Villiger oxidation?

Caprolactone

Cyclohexanol

Adipic acid

Hexanoic acid

62. In a mixed Cannizzaro reaction involving benzaldehyde and formaldehyde, which of the following will be the major products ?

Benzoic acid and methanol

Benzyl alcohol and formic acid

Phenol and formic acid

Benzoic acid and formic acid

63. What is the major product formed when ethyl acetate is refluxed with sodium ethoxide in ethanol, followed by acidification?

Diethyl malonate

Acetic acid

Butanoic acid

Ethyl acetoacetate

64. In the reaction: $A + 2HI \xrightarrow{Reflux}$ $Propane-1,2,3-tricarboxylic acid$ + $H_2O + CO_2$ . What is A?

Lactic acid

Tartaric acid

Malic acid

Citric acid

65. What type of compound is typically formed as the product of the Reformatsky reaction?

$\alpha$ -hydroxy ester

$\beta$ -hydroxy ester

$\alpha$ -halo ester

$\beta$ -halo ester

66. Which of the following statements about the compressibility factor Z is true ?

$Z=1$ indicates that the gas behaves as a real gas under all conditions of temperatures and pressures.

$Z<1$ generally indicates that the gas has a larger molar volume than an ideal gas.

$Z>1$ indicates that the gas is less compressible than the ideal gas.

The compressibility factor is always constant for a given gas regardless of temperature and pressure.

67. Which of the following statements accurately describes the relationship between the viscosity of a gas and temperature ?

The viscosity of a gas decreases with increasing temperature.

The viscosity of a gas is independent of temperature.

The viscosity of a gas increases with increasing temperature.

The viscosity of a gas is inversely proportional to the square of temperature.

68. What is the significance of the temperature 155 K for oxygen gas?

It is the temperature above which oxygen can be condensed into a liquid by increasing pressure alone.

It is the boiling point of oxygen at atmospheric pressure, below which it can exist as a liquid.

It is the critical temperature of oxygen, above which it cannot be liquefied regardless of pressure.

It is the temperature at which oxygen transitions directly from solid to gas without becoming liquid.

69. Which of the following instruments is commonly used to measure surface tension ?

Barometer

Stalagmometer

Calorimeter

Viscometer

70. The Miller indices for a plane with intercepts along the axes at 2a, 3b and 2c are

(232)

(131)

(1/2 1/3 1/2)

(323)

71. Number of atoms present in a body centred cubic (bcc) unit cell

1

2

3

4

72. The solubility product $K_{sp}$ of a sparingly soluble salt $A_2B$ is $4 \times 10^{-9}$ . The molar solubility of the salt is

$3 \times 10^{-4}$ mol $L^{-1}%

$3 \times 10^{-3}$ mol $L^{-1}%

$1 \times 10^{-3}$ mol $L^{-1}%

$1 \times 10^{-4}$ mol $L^{-1}%

73. $pK_a$ of an acid HA is 3.82. What will be the ratio of concentration of acid HA to concentration of $A^-$ to have a solution with pH 4.82?

1:1

2:1

10:1

1:10

74. For the reaction $4NO_{2(g)} + O_{2(g)} \rightleftharpoons 2N_2O_{5(g)}$

$K_p < K_c$

$K_p > K_c$

$K_p = K_c$

None of the above

75. The vapour pressure of a pure liquid A at 298 K is 50 mbar. When a solution B is prepared in A at the same temperature, the vapour pressure is found to be 25 mbar. The mole fraction of A in solution is

0.35

0.75

0.5

0.25

76. The freezing point of a solvent A was lowered by $0.55^{\circ}C$ on dissolving 2 g of a solute B in 100 g of A. The molar mass of solute B is (Given $K_f = 5.5 K \cdot kg \cdot mol^{-1}$ )

100

200

300

400

77. The boiling points of 0.0001 M solution of $BaCl_2$ and 0.0001 M solution of $AlCl_3$ in same solvent are $t_1^{\circ}C$ and $t_2^{\circ}C$ respectively. Identify the correct relation.

$t_1 = t_2$

$t_2 > t_1$

$t_1 > t_2$

$t_2 = t_1/2$

78. For a chemical reaction $2X_{2(g)} + 5Y_{2(g)} \rightarrow 2X_2Y_{5(g)}$ at $27^{\circ}C$ , the difference between $\Delta H$ and $\Delta U$ is Z. The ratio Z/R =

1500

-1500

2/7

7/2

79. Given that, i) $C + O_2 \rightarrow CO_2$ , $\Delta H^0 = -x$ kJ ii) $2CO + O_2 \rightarrow 2CO_2$ , $\Delta H^0 = -y$ kJ The enthalpy of formation of CO will be

$(y-2x)/2$

$(2x-y)/2$

$y-2x$

$2x-y$

80. 1 mol of an ideal gas at $27^{\circ}C$ is expanded reversibly from 3 L to 30 L. The entropy change is ( $R=2 cal \cdot K^{-1} \cdot mol^{-1}$ )

46

4.6

92

9.2

81. The work done during the expansion of an ideal gas from $2 \times 10^{-3} m^3$ to $1 \times 10^{-2} m^3$ at constant pressure of $1 \times 10^5 N m^{-2}$ is

800 kJ

-800 kJ

800 J

-800 J

82. If the bond energy of N-H bond = x cal $mol^{-1}$ , the change in internal energy in the following reaction is $NH_{3(g)} \rightarrow N_{(g)} + 3H_{(g)}$

x cal

2x cal

3x cal

4x cal

83. A substance has a heat capacity of $200 J/^{\circ}C$ . If 2 kJ of heat is added to this substance, what will be the increase in temperatures ?

20

10

0.01

0.001

84. The unit of rate constant in a zero order reaction is

mol $L^{-1} sec^{-1}%

$L mol^{-1} sec^{-1}%

L mol $sec^{-1}%

$sec^{-1}%

85. The minimum amount of energy that the reacting molecules should possess to produce effective collision is

Free energy

Internal energy

Threshold energy

Activation energy

86. The reaction $2N_2O_{5(g)}$ $\rightarrow 4NO_{2(g)}$ $+ O_{2(g)}$ is first order with respect to $N_2O_5$ . which of the following graphs would yield a straight line ?

$PN_2O_5$ vs time

$(P{N_2O_5})^{-1}$ vs time

$log(P{N_2O_5})$ vs time with positive slope

$log(P{N_2O_5})$ vs time with negative slope

87. The rate of reaction increases with increase in temperature. This is mainly due to

Increase in activation energy

Decrease in activation energy

Increase in effective no. of molecules for collision

Change in mechanism of the reaction

88. The unit of molar absorption coefficient is

$L mol^{-1} cm^{-1}

mol $L^{-1} m^{-1}

mol $L^{-1} cm^{-1}

$L mol^{-1} m^{-1}

89. The half life of a reaction is halved as the initial concentration of the reactant is doubled. What is the order of the reaction?

1

2

0

Fractional

90. In the electrochemical reaction $2Fe^{3+}(aq)$ $+ Sn^{2+}(aq)$ $\Rightarrow 2Fe^{2+}(aq)$ $+ Sn^{4+}(aq)$ , increasing the concentration of $Fe^{2+}(aq)$

Increases cell emf

Increases the current flow

Decreases the cell emf

Alter the pH of the solution

91. A compound shows a proton NMR peak at 240 Hz down-field from the TMS peak in a spectrometer operating at 60 MHz. What are the values of the chemical shifts in $\delta$ and $\tau$ scale in ppm relative to TMS?

6, 4

6, 3

4, 8

None of the above

92. Which of the following statement is false ?

Conductance of a solution decreases with increase in concentration.

Specific conductance of a solution decreases with increase in concentration.

Equivalent conductance of a solution decreases with increase in concentration.

Molar conductance of a solution decreases with increase in concentration.

93. Hypsochromic shift is due to

A shift of absorption to shorter wavelength

A shift of absorption to longer wavelength

An increase in the intensity of an absorption band

A decrease in the intensity of an absorption band

94. Choose the false statement.

The intensity of an absorption band depends on the size of the dipole moment change associated with the vibration.

The intensity of an absorption band depends on the no. of bonds responsible for the absorption.

It takes more energy to stretch a bond than to bend it.

The more polar the bond the less IR radiation it will absorb.

95. The relation between $D_e$ and $D_0$ , the two dissociation energies of an SHO is

$D_e = D_0 + h\nu/2$

$D_0 = D_e + h\nu/2$

$D_e = D_0 + h\nu$

$D_0 = D_e + h\nu$

96. The emf of Daniel cell at 298 K is $E_1$ for $Zn/ZnSO_4(0.01 M)$ // $CuSO_4(1 M)/Cu$ . When the concentration of $ZnSO_4$ is 1 M and that of $CuSO_4$ is 0.01 M, the emf changed to $E_2$ . What is the relation between $E_1$ and $E_2$ ?

$E_1 = E_2$

$E_2 = 0 \neq E_1$

$E_1 > E_2$

$E_1 < E_2$

97. From the list given below, which of the following elements can oxidise fluoride to fluorine ?

Mn

Co

Zn

None of the above

98. Which statement is true ?

Antistokes lines have higher frequency than stokes lines.

Antistokes lines have lower frequency than stokes lines.

Antistokes lines occur at higher wavelength than stokes lines.

Antistokes lines occur at same wavelength as that of Rayleigh line.

99. Calculate the ionic strength of 0.2 molal $K_2SO_4$

0.4 M

0.6 M

0.04 M

0.06 M

100. Calculate the liquid junction potential at 25 C between two solutions of HCl having mean ionic activities of 0.01 and 0.001, respectively. The transference number of $H^+$ ion ( $t^+$ ) in HCl may be taken as 0.83.

0.0039 V

0.0029 V

0.029 V

0.039 V