WBJEE Chemistry Question Paper 2013 (Eng)

Q. 1 – Q. 45 carry one mark each, for which only one option is correct. Any wrong answer will lead to deduction of 1/3 mark.

1.   In diborane, the number of electrons that account for bonding in the bridges is

(A) six         (B) two        (C) eight        (D) four

2.  The optically active molecule is

Ans is : C

3.   A van der Waals gas may behave ideally when

(A) The volume is very low

(B) The temperature is vey high

(C) The pressure is vey low

(D) The temperature, pressure and volume all are very high

4.  The half-life for decay of $^{14}C$ by β-emission is 5730 years. The fraction of $^{14}C$ decays, in a sample that is 22,920 years old, would be

(A) 1/8         (B) 1/16        (C) 7/8         (D) 15/16

5.   2-Methylepropane on monochlorination under photochemical condition give

(A) 2-Chloro-2-methylepropane as major product

(B) (1:1) Mixture of 1-chloro-2-methylepropane and 2-chloro-2-methylepropane

(C) 1-Chloro-2-methylepropane as major product

(D) (1:9) Mixture of 1-chloro-2-methylepropane and 2-chloro-2-methylepropane

6.   For a chemical reaction at 27°C, the activation energy is 600 R. The ratio of the rate constants at 327°C to that of at 27°C will be

(A) 2        (B) 40         (C) e          (D) e²

7.   Chlorine gas reacts with red hot calcium oxide to give

(A) Bleaching powder and dichlorine monoxide

(B) Bleaching powder and water

(C) Calcium chloride and chlorine dioxide

(D) Calcium chloride and oxygen

8.   Correct pair of compounds which gives blue colouration/precipitate and white precipitate, respectively, when their Lassaigne's test is separately done is

Ans is : (D)

9.   The change of entropy (dS) is defined as

(A) $dS=\delta q/T$       (B) dS = dH/T      (C) $dS=\delta q_{eqv}/T$       (D) dS = (dH-dG)/T

10.   In O₂ and H₂O₂, the O-O bond lengths are 1.21 and 1.48 Å respectively. In ozone, the average O-O bond length is

(A) 1.28 Å           (B) 1.18 Å          (C) 1.44 Å         (D) 1.52 Å      

11.  The IUPAC name of the compound X is

(A) 4-cyano-4-methyle-2-oxopentane

(B) 2-cyano-2-methyle-4-oxopentane

(C) 2,2-dimethyle-4-oxopentanenitrile

(D) 4-cyano-4-methyle-2-pentanone

12.  At 25°C, the solubility product of a salt of MX₂ type is 3.2 x 10^-8 in water. The solubility (in moles/lit) of MX₂ in water at the same temperature will be

(A) 1.2 x 10^-3         (B) 2 x 10^-3         (C) 3.2 x 10^-3         (D) 1.75 x 10^-3

13.   In SOCl₂, the Cl-S-Cl and Cl-S-O bond angles are

(A) 130° and 115°        (B) 106° and 96°         (C) 107° and 108°         (D) 96° and 106°

14.  (+)-2-chloro-2-phenylethane in toluene racemises slowly in the presence of small amount of SbCl₅, due to the formation of

(A) carbanion          (B) carbene         (C) free-radical         (D) carbocation

15.  Acid catalysed hydrolysis of ethyle acetate follows a pseudo-first order kinetics with respect to ester. If the reaction is carried out with large excess of ester, the order with respect to ester will be

(A) 1.5          (B) 0           (C)  2         (D) 1

16.  The different colours of litmus in acidic, neutral and basic solutions are, respectively,

(A) Red, orange and blue

(B) Blue, violet and red

(C) Red, colourless and blue

(D) Red, violet and blue

17.  Baeyer's reagent is

(A) Alkaline potassium permanganate

(B) Acidified potassium permanganate

(C) Neutral potassium permanganate

(D) Alkaline potassium manganate

18.  The correct order of equivalent conductances at infinite dilution in water at room temperature for

$H^+, K^+, CH_3COO^-$ and $HO^-$ ions is

(A) $HO^->H^+>K^+>CH_3COO^-$

(B) $H^+>HO^->K^+>CH_3COO^-$

(C) $H^+>K^+>HO^->CH_3COO^-$

(D) $H^+>K^+>CH_3COO^->HO^-$

19.  Nitric acid can be obtained from ammonia via the formations of the intermediate compounds

(A) Nitric oxides and nitrogen dioxides

(B) Nitrogen and nitric oxides

(C) Nitric oxide and dinitrogen pentoxide

(D) Nitrogen and nitrous oxide

20.  In the following species, the one which is likely to be the intermediate during benzoin condensation of benzaldehyde, is

Ans is : (C)

21.  The correct order of acid strength of the following substituted phenols in water at 28°C is

(A) p-nitrophenol < p-fluorophenol < p-chlorophenol

(B) p-chlorophenol < p-fluorophenol < p-nitrophenol

(C) p-fluorophenol < p-chlorophenol < p-nitrophenol

(D) p-fluorophenol < p-nitrophenol < p-chlorophenol

22.   For isothermal expansion of an ideal gas, the correct combination of the thermodynamic parameters will be

(A) ΔU = 0, Q = 0, w ≠ 0 and ΔH ≠ 0

(B) ΔU ≠ 0, Q ≠ 0, w ≠ 0 and ΔH ≠ 0

(C) ΔU = 0, Q ≠ 0, w = 0 and ΔH ≠ 0

(D) ΔU = 0, Q ≠ 0, w ≠ 0 and ΔH ≠ 0

23.  Addition of excess potassium iodide solution to a solution of mercuric chloride gives the halide complex

(A) tetrahedral $K_2[HgI_4]$

(B) trigonal $K[HgI_3]$

(C) linear $Hg_2I_2$

(D) square planar $K_2[HgCl_2I_2]$

24.   Amongst the following, the one which can exist in free state as a stable compound is

(A) $C_7H_9O$        (B) $C_8H_{12}O$         (C) $C_6H_{11}O$          (D) $C_{10}H_{17}O_2$

25.  A conductivity cell has been calibrated with a 0.01 M 1:1 electrolyte solution (specific conductances k=1.25 x 10^-3 S cm^-1) in the cell and the measured resistance was 800 ohms at 25°C. The constant will be

(A) 1.02 cm^-1        (B)  0.102 cm^-1         (C) 1.00 cm^-1        (D) 0.5 cm^-1

26.  The orange solid on heating gives a colourless gas and a green solid which can be reduced to metal by aluminium powder. The orange and the green solids are, respectively

(A) $(NH_4)_2Cr_2O_7$ and $Cr_2O_3$

(B) $Na_2Cr_2O_7$ and $Cr_2O_3$

(C) $K_2Cr_2O_7$ and $CrO_3$

(D) $(NH_4)_2Cr_2O_4$ and $CrO_3$

27.  The best method for the preparation of 2,2-dimethylbutane is via the reaction of

(A) $Me_3CBr$ and $MeCH_2Br$ in Na/ether

(B) $(Me_3C)_2CuLi$ and $MeCH_2Br$

(C) $(MeCH_2)_2CuLi$ and $Me_3CBr$

(D) $Me_3CMgI$ and $MeCH_2I$

28.  The condition of spontaneity of process is

(A) lowering of entropy at constant temperature and pressure

(B) lowering of Gibbs free energy of system at constant temperature and pressure

(C) increase of entropy of system at constant temperature and pressure

(D) increase of Gibbs free energy of the universe at constant temperature and pressure

29.   The increasing order of O-N-O bond angle in the species $NO_2, NO_2^+$ and $NO_2^-$ is

(A) $NO_2^+ < NO_2 < NO_2^-$

(B) $NO_2 < NO_2^- < NO_2^+$

(C) $NO_2^+ < NO_2^- < NO_2$

(D) $NO_2 < NO_2^+ < NO_2^-$

Ans : No option

30.   The correct structure of the dipeptide gly-ala is

Ans is : (C)

31.   Equivalent conductivity at infinite dilution for sodium-potassium oxalate $((COO^-)_2Na^+K^+)$ will be [given, molar conductivities of oxalate, $K^+$ and $Na^+$ ions at infinite dilution are 148.2, 50.1, 73.5 S cm²mol^-1, respectively]

(A) 271.8 S cm²eq^-1          (B) 67.95 S cm²eq^-1         (C) 543.6 S cm²eq^-1        (D) 135.9 S cm²eq^-1

32.   For $BCl_3, AlCl_3$ and $GaCl_3$ the increasing order of ionic character is

(A) $BCl_3 < AlCl_3 < GaCl_3$

(B) $GaCl_3 < AlCl_3 < BCl_3$

(C) $BCl_3 < GaCl_3 < AlCl_3$

(D) $AlCl_3 < BCl_3 < GaCl_3$

33.   At 25°C, pH of a 10^-8 M aqueous KOH solution will be

(A) 6.0          (B) 7.02         (C) 8.02         (D) 9.02

34.  The reaction of nitroprusside anion with sulphide ion gives purple colouration due to the formation of

(A) the tetranionic complex of iron(II) coordinating to one $NOS^-$ ion

(B) the dianionic complex of iron(II) coordinating to one $NCS^-$ ion

(C) the trianionic complex of iron(III) coordinating to one $NOS^-$ ion

(D) the tetranionic complex of iron(III) coordinating to one $NCS^-$ ion

35.   An optically active compound having molecular formula $C_8H_{16}$ on ozonolysis gives acetone as one of the products. The structure of the compound is

Ans is : B

36.   Mixing of two different ideal gases under isothermal reversible condition will lead to

(A) increase of Gibbs free energy of the system

(B) no change of entropy of the system

(C) increase of entropy of the system

(D) increase of enthalpy of the system

37.  The ground state electronic configuration of CO molecule is

(A) $1 \sigma^2 2 \sigma^2 1 \pi^4 3 \sigma^2$

(B) $1\sigma^2 2 \sigma^2 3 \sigma^2 1 \pi^2 2 \pi^2$

(C) $1 \sigma^2 2 \sigma^2 1 \pi^2 3 \sigma^2 2 \pi^2$

(D) $1 \sigma^2 1 \pi^4 2 \sigma^2 3 \sigma^2$

38.  When aniline is nitrated with nitrating mixture in ice cold condition, the major product obtained is

(A) p-nitroaniline        (B) 2,4-dinitroaniline        (C)  o-notroaniline         (D) m-nitroaniline

39.  The measured freezing point depression for a 0.1 m aqueous $CH_3COOH$ solution is 19 °C. The acid dissiociation constant $K_a$ at the concentration will be (Given $K_f$, the molal cryoscopic constant = 1.86 K kg mol^-1)

(A) 4.76 x 10^-5        (B) 4 x 10^-5        (C) 8 x 10^-5        (D) 2 x 10^-5

40.  The ore chromite is

(A) $FeCr_2O_4$         (B) $CoCr_2O_3$         (C) $CrFe_2O_4$         (D) $FeCr_2O_3$

41.  'Sulphan' is

(A) a mixture of $SO_3$ and $H_2SO_5$

(B) 100% conc. $H_2SO_4$

(C) a mixture of gupsum and conc. $H_2SO_4$

(D) 100% oleum (a mixture of 100% $SO_3$ in 100% $H_2SO_4$)

42.   Pressure-volume (PV) work done by an ideal gaseous system at constant volume is (where E is internal energy of the system)

(A) -ΔP/P         (B) zero          (C) -VΔP         (D) -ΔE

43.  Amongst $[NiCl_4]^{2-}$, $[Ni(H_2O)_6]^{2+}$, $[Ni(PPh_3)_2Cl_2]$, $[Ni(CO)_4]$ and

$[Ni(CN)_4]^{2-}$, the paramagnetic species are

(A) $[NiCl_4]^{2-}$, $[Ni(H_2O)_6]^{2+}$, $[Ni(PPh_3)_2Cl_2]$

(B) $[Ni(CO)_4]$, $[Ni(PPh_3)_2Cl_2]$, $[NiCl_4]^{2-}$

(C) $[Ni(CN)_4]^{2-}$, $[Ni(H_2O)_6]^{2+}$, $[NiCl_4]^{2-}$

(D) $[Ni(PPh_3)_2Cl_2]$, $[Ni(CO)_4]$, $[Ni(CN)_4]^{2-}$

44.   Number of hydrogen ions present in 10 millionth part of 1.33 cm³ of pure water at 25°C is

(A) 6.023 million         (B) 60 million         (C) 8.01 million         (D) 80.23 million

45.  Ribose and 2-deoxyribose can be differentiated by

(A) Fehling's reagent        (B) Tollens's reagent        (C)  Barfoed's reagent        (D) Osazone formation

Q. 46 – Q. 55 carry two marks each, for which only one option is correct. Any wrong answer will lead to deduction of 2/3 mark

46.  The standard Gibbs free energy change $(\Delta G^0)$ at 25°C for the dissociation of $N_2O_4(g)$ to $NO_2(g)$ is (given, equilibrium constant = 0.15, R = 8.314 JK/mol)

(A) 1.1 kj        (B) 4.7 kj         (C) 8.1 kj          (D) 38.2 kj

47.   Bromination of PhCOMe in acetic acid medium produces mainly

Ans is : D

48.  Silicone oil is obtained from the hydrolysis and polymerisation of

(A) trimethylchlorosilane and dimethyldichlorosilane

(B) trimethylchlorosilane and methyldichlorosilane

(C) methylchlorosilane and dimethyldichlorosilane

(D) triethylchlorosilane and diethyldichlorosilane

49.  Tratment of with $NaNH_2/liq.NH_3$ gives

Ans is : D

50.   Identify the CORRECT statement

(A) Quantum numbers (n, l, m, s) are obtained arbitrarily

(B) All the quantum numbers (n, l, m, s) for any pair of electrons in an atom can be identical under special circumstance

(C) All the quantum numbers (n, l, m, s) may not be required to describe an electron of an atom completely

(D) All the quantum numbers (n, l, m, s) are required to describe an electron of an atom completely

51.  In borax the number of B-O-B links and B-OH bonds present are, respectively,

(A) Five and four       (B) Four and five        (C) Three and four        (D) Five and five

52.  Reaction of benzene with $Me_3COCl$ in the presence of anhydrous $AlCl_3$ gives

Ans is : B

53.  1 x 10^-3 mole of HCl is added to a buffer solution made up of 0.01M acetic acid and 0.01M sodium acetate. The final pH of the buffer will be (given, pK_a of acetic acid is 4.75 at 25°C)

(A) 4.60        (B) 4.66        (C) 4.75        (D) 4.8

54.  The best method for preparation of $Me_3CCN$ is

(A) To react $Me_3COH$ with HCN

(B) To react $Me_3CBr$ with NaCN

(C) To react $Me_3CMgBr$ with ClCN

(D) To react $Me_3CLi$ with $NH_2CN$

55.  On heating, chloric acid decompose to

(A) $HClO_4, Cl_2, O_2$ and $H_2O$

(B) $HClO_2, Cl_2, O_2$ and $H_2O$

(C) $HClO, Cl_2O$ and $H_2O_2$

(D) $HCl, HClO, Cl_2O$ and $H_2O$

Q. 56 – Q. 60 carry two marks each, for which one or more than one options may be correct. Marking of correct options will lead to a maximum mark of two on pro rata basis. There will be no negative marking for these questions. However, any marking of wrong option will lead to award of zero mark against the respective question-irrespective of the number of correct options marked.

56.   Consider the following reaction for $2NO_2(g)+F_2(g)\rightarrow 2NO_2F(g)$. The expression for the rate of reaction in terms of the rate of change of partial pressure of reactant and product is/are

(A) rate = $-{1 \over 2}[dp(NO_2)/dt]$

(B) rate = ${1 \over 2}[dp(NO_2)/dt]$

(C) rate = $-{1 \over 2}[dp(NO_2F)/dt]$

(D) rate = ${1 \over 2}[dp(NO_2F)/dt]$

57.   Tautomerism is exhibited by

Ans is : A

58.  The important advantage(s) of Lintz and Donawitz (L.D) process for the manufacture of steel is/are

(A) The process is very quick

(B) Operating costs are low

(C) Better quality steel is obtained

(D) Scrap iron can be used

59.   In basic medium the amount of $Ni^{2+}$ in a solution can be estimated with the dimethylglyoxime reagent. The correct statement(s) about the reaction and the product is/are

(A) In ammoniacal solution $Ni^{2+}$ salts give cherry-red precipitate of nickel (II) dimethylglyoximate

(B) Two dimethylglyoximate units are bound to one $Ni^{2+}$

(C) In the complex two dimethylglyoximate units are hydrogen bonded to each other

(D) Each dimethylglyoximate unit forms a six-membered chelate ring with $Ni^{2+}$

60.   Correct statement(s) in cases of n-butanol and t-butanol is/are

(A) Both are having equal solubility in water

(B) t-butanol is more soluble in water than n-butanol

(C) Boiling point of t-butanol is lower than n-butanol

(D) Boiling point of n-butanol is lower than t-butanol

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