1.    The correct statement describing the relationship between

    

    (a) X and Y are resonance structures and Z is a tautomer

    (b) X and Y are tautomers and Z is a resonance structure.

    (c) X, Y and Z are all resonance structures.

    (d) X, Y and Z are all tautomers.

Ans.    a

Sol.    In resolving structure, there is movement of l.p. and only, but in tautomerism there is movement of 'H' atom.

    So, 'X' and 'Y' are resonating structure and Z is tautomer.

    Correct answer is (a)

2.    Among the following, the correct statement concerning the optical activity is:

    (a) A molecule containing two or more chiral centres is always optically active.

    (b) A molecule containing just one chiral centres is always optically active.

    (c) A molecule possessing alternating axis of symmetry is optically active

    (d) An optically active molecule should have at least one chiral centre.

Ans.    b

Sol.    For a molecule to be chiral, there should not have any of these three symmetries

    (i) Alternate axis of symmetry

    (ii) Plane of symmetry

    (iii) Centre of symmetry

    If there are more than one chiral centre in a compound, then it can have any of the above three symmetric elements, so it can become optically inactive.

    Correct option is (b)

3.    The correct order of acidity among

    

    (a) (i) < (ii) < (iii) < (iv)

    (b) (iv) < (i) < (iii) < (ii)

    (c) (ii) < (i) < (iii) < (iv)

    (d) (ii) < (iv) < (i) < (iii)

Ans.    b

Sol.    (b) A strong acid has conjugate base most stable (i.e. weakest base).

    

    

    

    Due to +I effect of CH₃ group conjugate base of (iii) is more basic than (i). So, (iii) is less acidic than (i).

    

    As conjugate base of (iv) is strongest base w.r.t. conjugate base of (i), (ii) and (iii), so (iv) is weaker acid.

    Acidity order (iv) < (iii) < (i) < (ii)

    Correct option is (b)

4.    The major product obtained in the following reaction.

     is

    (a)

    (b)

    (c)

    (d)

Ans.    c

Sol.    

5.    The major product of the following reaction

    

    (a)

    (b)

    (c)

    (d)

Ans.    d

Sol.    Chemical transformation involved in above chemical reaction can be illustrated as

    

    

    Correct option is (d)

6.    The major product obtained in the following reaction

    

    (a)

    (b)

    (c)

    (d)

Ans.    a

Sol.    Chemical transformation involved in above chemical reaction can be illustrated as

    

    Correct option is (a)

7.    R(–)2–Bromooctane on treatment with aqueous KOH mainly gives 2-octanol that is:

    (a) Optically active with 'R' configuration

    (b) Optically active with 'S' configuration

    (c) A racemic mixture

    (d) A meso compound

Ans.    b

Sol.    As the reaction is S_N2predominantly, so inverted product is formed.

    Correct option is (b)

8.    The major product obtained in the following reaction

    

    (a)

    (b)

    (c)

    (d)

Ans.    b

Sol.    The reaction is Beckmann rearrangement, so the group anti to leaving group i.e. Ph-migrates.

    Correct option is (b)

9.    The major product obtained in the following reaction

    

    (a)

    (b)

    (c)

    (d)

Ans.    c

Sol.    Chemical transformation involved in above chemical reaction can be illustrated as

    

    

    Correct option is (c)

10.    The products of the following reaction

    

    (a)

    (b)

    (c)

    (d)

Ans.    a

Sol.    Above reaction is Cannizzaro reaction

    Correct option is (a)

11.    When one mole of ice is converted to water at 0ºC and 1 atm, the work done (1 atm) is:

    (a) 1.1 × 10^–4

    (b) 2.0 × 10^–3

    (c) 2.0 × 10^–4

    (d) 1.1 × 10^–5

Ans.    b

Sol.    

    

    Correct option is (b)

12.    When 100 g of water is reversibly heated from 50ºC to 75ºC at 1 atm, the change in entropy (JK^–1) of the universe is:

    (a) –0.31

    (b) 0.31

    (c) 0

    (d) 3.1

Ans.    c

Sol.    

    Correct option is (c)

13.    For a zero order reaction, units of the rate constant is expressed as

    (a) M¹s^–1

    (b) M⁰s^–1

    (c) M^–1s^–1

    (d) M⁰s⁰

Ans.    a

Sol.    

14.    1 × 10^–6 moles of the enzyme carbonic anhyrase dehydrates H₂CO₃ to produce 0.6 mol of CO₂ per second. The turnover number of the enzyme is:

    (a) N_A × 6 × 10^–5

    (b) (1/6) × 10^–5

    (c) (6 × 10⁵) / N_A

    (d) 6 × 10⁵

Ans.    d

Sol.    Turnover number = number of moles of products formed per mole of catalyst (enzyme)

    

    Correct option is (d)

15.    Given that the most probable speed of oxygen gas is 1000 ms^–1, the mean/average speed (ms^–1) under the same conditions is:

    (a) 1224

    (b) 1128

    (c) 886

    (d) 816

Ans.    b

Sol.    

    Correct option is (b)

16.    If the electron were spin 3/2 particles, instead of spin 1/2, then the number of electrons that can be accomodated in a level are

    (a) 2

    (b) 3

    (c) 4

    (d) 5

Ans.    3

Sol.     then m_s can have value, from +s to –s, m_s =

    As 4-values of m_s are possible for so 4-electrons can be accomodated, without violating Pauli's exclusion principle.

    Correct option is (c)

17.    For a particle in a cubic box, the total number of quantum number needed to specify its state are

    (a) 1

    (b) 3

    (c) 4

    (d) 9

Ans.    c

Sol.    Wave function for a particle in 3-D cubic box (box side = L)

    

    where n_x, n_y, n_z are 3-quantum numbers.

    Correct option is (c)

18.    The maximum number of phases that can co-exist in equilibrium for a one component system is:

    (a) 1

    (b) 2

    (c) 3

    (d) 4

Ans.    c

Sol.    As F(minimum) = 0

    

19.    With increasing pressure, the temperature range over which the liquid state is stable.

    (a) Decreases

    (b) Increases

    (c) Remains constant

    (d) Decreases till the critical pressure and then increases.

Ans.    b

Sol.    

    (P-T-phase diagram of H₂O)

    As, P₁ > P₂ > P₃, we see from the phase diagram that as the pressure is increased, the temperature range over which liquid phase is stable increases.

    Correct option is (b)

20.    The conductance at infinite dilution follows the order

    (a) Li⁺ > Na⁺ > K⁺

    (b) Na⁺ > Li⁺ > K⁺

    (c) K⁺ > Li⁺ > Na⁺

    (d) K⁺ > Na⁺ > Li⁺

Ans.    d

Sol.    As the cation gets, hydrated, its mobility (conductivity) decreases due to its increased size.

    

    As Li⁺, Na⁺, K⁺ all have same charge but radius has order as Li⁺ < Na⁺ < K⁺. So, net size after hydrolysis is Li⁺ > Na⁺ > K⁺

    So mobility/conductivity has reverse order of size.

    Correct option is (d)

21.    The V-shape of SO₂ is due to the presence of

    (a)

    (b)

    (c)

    (d)

Ans.    c

Sol.     and 1 l.p. on sulfur. But bond has no role in shape

    Correct option is (c)

22.    The correct order of the mean bond energies in the binary hydrides is:

    (a) CH₄ > NH₃ > H₂O > HF

    (b) NH₃ > CH₄ > H₂O > HF

    (c) HF > H₂O > CH₄ > NH₃

    (d) HF > H₂O > NH₃ > CH₄

Ans.    d

Sol.    In H-F, H₂O, NH₃ and CH₄ all bonds are formed by 1s(H) and sp³ orbital of F, O, N and C respectively.

    As ionic character in a bond increases the net bond strength increases.

     has covalent bond strength as well as ionic force of attraction between

    Correct option is (d)

23.    In CsCl structure, the number of Cs⁺ ions that occupy second nearest neighbour locations of a Cs⁺ ion is:

    (a) 6

    (b) 8

    (c) 10

    (d) 12

Ans.    b

Sol.    Correct option is (b)

24.    In the process

    

    X is:

    (a)

    (b)

    (c)

    (d)

Ans.    a

Sol.    

    Correct option is (a)

25.    For tetrahedral complexes, which always exhibit high spin states, the maximum CFSE (crystal field stabilization energy) is:

    (a) –8 Dq

    (b) –12 Dq

    (c) –16 Dq

    (d) –20Dq

Ans.    b

Sol.    

    Maximum CFSE is possible for e², t₂⁰ or e⁴, t₂³ configuration.

    Therefore, CFSE (maximum) = –2 × 6 Dq = –12 Dq.

    Correct option is (b)

26.    The most abundant element in earth's crust is:

    (a) Aluminium

    (b) Iron

    (c) Silicon

    (d) Oxygen

Ans.    d

Sol.    Abundance in the earth crust: O > Si > Al > Fe.

    Correct option is (d)

27.    Metal-carbon multiple bonds in metal carbonyl are preferably identified from the stretching frequency of

    (a) Carbon-oxygen bond

    (b) Metal-carbon bond

    (c) Metal-oxygen bond

    (d) Carbon-carbon bond

Ans.    a

Sol.    As metal donates electrons to antibonding of CO, C – O bond stretching frequency decreases, which can be studied by IR-spectroscopy.

    Correct option is (a)

28.    In general, magnetic moment of paramagnetic complexes varies with temperature as

    (a) T^2–

    (b) T

    (c) T²

    (d) T^–1

Ans.    d

Sol.    Correct option is (d)

29.    The compound having an S-S single bond is

    (a) H₂S₂O₃

    (b) H₂S₂O₄

    (c) H₂S₂O₇

    (d) H₂S₂O₈

Ans.    b

Sol.    

    Correct option is (b)

30.    In a reaction, Na₂S₂O₃ is converted to Na₂S₄O₆. The equivalent weight of Na₂S₂O₃ for this reaction is (mol. wt of Na₂S₂O₃ = M)

    (a) M

    (b) M/4

    (c) M/2

    (d) M/3

Ans.    a

Sol.    

    Net change in oxidation number of 'S' per mole

    

    Correct option is (a)

31.    (a) Identify A, B and C in the following reaction sequence.

    

    (b) Identify D in the following reaction and suggest a suitable mechanism for its formation.

    

Sol.    

    

    

32.    (a) Explain with the help of mechanisms, the observed stereoselectivity in the following epoxide formation reactions.

    

    (b) Explain on the basis of conformational analysis why (1R, 2R)-1, 2-dimethyl-cyclohexane is optically inactive at room temperature.

Sol.    (a)

    

    

    As (I) and (II) exist in equilibrium and also (I) and (II) are mirror images of each other. (i.e. I and II are enantiomers)

    As (1R, 2S)-1, 2-dimethylcyclohexane exists as equilibrium mixture of 50% (I) and 50% (II), So due to external compensation, it is optically inactive.

33.    (a) Identify E, F and G in the following synthetic transformation:

    

    (b) An optically active compound H (C₅H₆O) on treatment with H₂ in the presence of Lindlar's catalyst gave a compound I (C₅H₈O). Upon hydrogenation with H₂ and Pd/C, compound H gave J(C₅H₁₂O). Both I and J were found to be optically inactive. Identify H, I and J.

Sol.    

    

34.    (a) A disaccharide K gives a silver mirror with Tollen's reagent. Treatment of K with MeOH/HCl gives a monomethyl derivative L, which does not react with Tollen's reagent. Methylation of K with Me₂SO₄ and NaOH affords an octamethyl derivative of K, which upon acidic hydrolysis gives a 1:1 mixture of 2, 3, 4, 6-tetra-O-methyl-D-glucose and 2, 3, 4-tri-O-methyl-D-glucose. Disaccharide K is also hydrolysed by the enzyme maltase. Identify K and L with proper stereochemistry.

    (b) Identify M and N in the following reaction sequence

    

Sol.    (a)

    

    

35.    In the following reaction sequence, identify P, R and S. Suggest suitable mechanism for the conversion of

    

Sol.    

    

    

    

    

36.    

    (i) Identify A and B.

    (ii) What is the role of H₂O₂ in (I) and how does A favour the formation of Cr³⁺?

    (iii) What is the role of H₂O₂ in (II) and how does B favour the formation CrO₄^2–?

    (b) With the help of equations, illustrate the role of a cis-1, 2-diol in the titration of boric acid with sodium hydroxide.

Sol.    

    (ii) In reaction (I), H₂O₂ acts as a bidentate ligand as well as a reducing agent in acidic medium in order to form CrO(O₂)₂ and Cr⁺³.

    In acidic condition (i.e. in presence of H⁺) H₂O₂ acts as an reducing agent such that Cr⁺⁶ in Cr₂O₇^2– gets reduced to Cr⁺³.

    Oxidation Half-Cell:

    

    (iii) H₂O₂ in reaction (2) act as a oxidizing agent.

    In presence of OH^– the recuction potention of H₂O₂ is more than reduction potential of Cr⁺⁶ / Cr⁺³.

    

    (b) As H₃BO₃ is a weak lewis monobasic acid, so it is titrated with NaOH, a sharp end point is not obtained because no indicator is present in the range of end point.

    

    

    Once cis-diol is added to the above titration mixture, it consumes Na[B(OH)₄] so net reaction proceeds forward, So, H₃BO₃ acts as a stronger acid and can be titrated in presence of phenophthalein indicator

37.    (a) Draw the structure of anionic Ca(II)-EDTA chelate. How many rings are formed in the chelate and specify the number of atoms in each ring?

    (b) Based on VSEPR theory draw the most stable structure of CIF₃ and XeF₄.

Sol.    (a) [Ca(EDTA)]^2–

    

    There are total 5-rings in which 4 rings with N and O linkage to metal ion. and 1 ring with N and N linkage to metal ion.

    There are 5 atoms in each ring, so all rings are five membered

    

    trigonal bypyramidal geometry

    

38.    (a) Identify A, B and C in the following reaction scheme

    

    (b) From the Ellingham diagram given below, identify the metal oxide that can be reduced at a lower temperature by carbon. Justify.

    

Sol.    

    

    As after temperature T₁ the of reaction, becomes more negative than reaction, So carbon can reduce MgO above temperature T₁ but of reaction becomes more -ve than Ca CaO reaction only above T₂.

    As T₁ < T₂

    So, MgO can be reduced at lower temperature than CaO.

39.    (a) For the complexes [FeF₆]^3– and [Fe(CN)₆]^3–.

    (i) Show the hybridization using VB(valence bond) theory

    (ii) Calculate the CFSE (crystal field stabilization energy)

    (b) Identify the dark blue complex formed when [Fe(CN)₆]^3– is treated with FeSO₄ and account for the origin of its colour.

Sol.    

    

    

    

40.    (a) Consider the equilibrium,

    At a constant pressure of 1 atm, A dissociated to the extent of 50% at 500 K. Calculate (kJ mol^–1) for the reaction.

    (b) Consider the following redox system.

    

    Calculate the pH of the solution at 298 K, if the redox potential of the system is 0.817 V.

Sol.    

    

41.    (a) A stream of oxygen molecules at 500 K exists from a pin-hole in an oven and strikes a slit that selects the molecules travelling in a specific direction. Given that the pressure outside the oven 2.5 × 10^–7 atm, estimate the maximum distance at which the slit must be placed from the pin-hole, in order to produce a collimated beam of oxygen (Radius of O₂ = 1.8 × 10^–10 m)

    (b) Liquid water is to be circulated to transfer heat from a source to a sink at 1 atm. Considering this arrangement as a Carnot engine, calculate the maximum theoretical efficiency that can be expected from the system.

Sol.    

    Let "L" be the distance at which slit must be placed from the pin-hole. In order to obtain collimated beam, the entering O₂ molecule should not collide with any other molecule inside.

    So, L should be equal to the mean free path of the O₂ molecule.

    

    d = diameter of O₂ molecule.

    1 atm = 1.01 × 10⁵ N/m² = 0.474 m = 47.4 cm

    (b) As at 1 atm water an exist in liquid state between temperature range of 0ºC to 100ºC.

    So, source temperature can be maximum value (T₁) = 100ºC = 373 K.

    and sink temperature can be minimum value (T₂) = 0ºC = 273 K

    

42.    (a) Using Heisenberg's uncertainty principle, derive an expression for the approximate ground state energy of a particular of mass m in a one dimensional box of length L.

    (b) The rate of a chemical reaction doubles when the temperature is changed from 300 K to 310 K.

    Calculate activation energy in kJ mol^–1

Sol.    (a) From Heisenberg's uncertainity principle

    

    Maximum uncertainity in measurement of position can be approximated to box length 'L'

    

    Momentum of particle of mass 'm' can be approximated to error in momentum measurement,

    So,    Energy of particle (E) = K.E.

    

    Doubling of rate of reaction is related to doubling of rate constant,

    

43.    (a) Consider the reaction.

    

    Assuming ideal behaviour, calculate when 1 mol of CH₄ is completely oxidized at STP.

    (b) A photochemical reaction was carried out using monochromatic radiation (490 nm) of intensity 100 W. When the sample was irradiated for 30 min, 0.3 mol of the reactant was decomposed. Estimat the quantum efficiency assuming 50% absorption.

Sol.    

    

    

44.    

    for a pure substance, show that C_P – C_V = R for 1 mole of an ideal gas.

    (b) Find the eigenvalues of the following 3 × 3 matrix given that 2 is one of the eigen values. Compute the determinant of matrix using the eigen values.

    

Sol.