1. The compound, which

(i) Reacts rapidly with acetyl chloride

(ii) Does not react with 2, 4-dinitrophenylhydrazine and

(iii) Does not form a yellow precipitate with excess of iodine in aqueous alkali is

(a) Acetone

(b) Diethyl ether

(c) 2-methyl-2-propanol

(d) Ethanol

Ans. C

Sol.

2.

(a) Identical

(b) Diastereomeric

(c) Enantiomeric

(d) Constitutionally isomeric

Ans. d

Sol.

As connectivity of atoms in (1) and (2) is different, so they are constitutional (structural) isomers.

Correct option is (d)

3. The correct order of dipole moments of the following compounds is

(1) CH₃CH₂CH₂CHO

(2) CH₃CH = CHCHO

(3) CH₃CH₂CH = CH₂

(a)

(b)

(c)

(d)

Ans. d

Sol. Dipole moment in above molecule can be represented as

Maximum charge separation (r).

Among these three the has maximum dipole moment followed by because as we know the dipole moment is defined by following equation

where, q = magnitude of charge

r = separation between charge.

bond has larger dipole moment than

As (2) has larger charge separation than (1),

Correct option is (d)

4. Which one of the following compounds gives positive test for both nitrogen and halogen with its Lassaigne's extract?

(a) CH₃NH₂.HCl

(b) NH₂OH.HCl

(c) NH₄Cl

(d) H₂NNH₂.HCl

Ans. a

Sol. In Lassaigne's test of an organic compound we get test for CN^– and X^–, if the compound has nitrogen and halogen.

For formation of CN^–, compound must have carbon.

Correct option is (a)

5. Which one of the following compounds is optically active?

(a) 1

(b) 2

(c) 3

(d) 4

Ans. d

Sol. Compound (1), (2) and (3) has plane of symmetry, so they are optically inactive. While (4) does not contain plane of symmetry so (4) is optically active.

Correct option is (d)

6. The compounds that react with aqueous NaHCO₃ to release CO₂ are

(a) 1 and 3

(b) 2 and 4

(c) 2 and 3

(d) 1 and 4

Ans. b

Sol.

Correct option is (b)

7. The complementary strand of DNA for the following single stranded DNA sequence,

5´–A–T–C–A–T–G–C–3´ is

(a) 5´–A–T–C–A–T–G–C–3´

(b) 5´–T–A–G–T–A–C–G–3´

(c) 5´–G–C–A–T–G–A–T–3´

(d) 5´–C–G–T–A–C–T–A–3´

Ans. c

Sol. In complementary strand 'A' will be replaced by 'T' and vice-versa and 'G' by 'C'and vice-versa. Therefore, complementary stand will be determined as

Correct option is (c)

8. The value of 'n' for the following molecule according to Huckel's rule is

(a) 16

(b) 4

(c) 3

(d) 14

Ans. c

Sol. There are 16 in the molecule, but this can not be aromatic by Huckel rule, so in order to be aromatic and to follow Huckel rule, only 14 should be involved in making the ring current.

here only 14 will form the ring current.

Correct option is (c).

9. Which one of the following compounds reacts with nitrous acid to give the product [P]?

(a)

(b)

(c)

(d)

Ans. a

Sol. (P) can be prepared by following chemical transformation

Only (a) will give the (P) because the stereochemistry of (P) can only be derived from (a).

Correct option is (a)

10. The main product obtained in the following reaction is

(a)

(b)

(c)

(d)

Ans. a

Sol. The compounds containing acidic hydrogen when reacted with RMgX. First acid base reaction occurs, acid alkene will form

Chemical transformation involved in above chemical reaction can be illustrated as

Correct option is (a)

11. For a reaction with rate equation –dC/dt = kC², C₀ and C are the concentrations of the reactant at time 0 and t respectively. If 10 minutes were required for C₀ to become C₀/2, the time required for C₀ to become C₀/4 is:

(a) 10 min

(b) 20 min

(c) 30 min

(d) 40 min

Ans. c

Sol.

Correct option is (c)

12. For a cyclic process performed by an ideal gas, changes in some thermodynamic functions are zero. Indicate the set in which all the functions are zero

(a)

(b)

(c)

(d)

Ans. d

Sol. As E, S, H and A are state functions, so they are path independent and in a cyclic process, net change is zero.

Correct option is (d)

13. The plot of Gibb's free energy G and the extent of a reaction is given below for the reaction . If and are the chemical potentials of A and B respectively, the incorrect statement is:

(a)

(b)

(c)

(d) At equilibrium, the composition of the reaction mixture can be identified.

Ans. c

Sol.

At point 'Z', net reaction is backward,

Correct option is (c)

14. The overlap between the atomic orbitals sketched below is:

(a) Positive

(b) Negative

(c) Zero

(d) No overlap

Ans. a

Sol. Correct option is (a)

15. The pH of a 1.0 × 10^–3 M solution of a weak acid HA is 4.0. The acid dissociation constant K_a is:

(a) 1.0 × 10^–3

(b) 1.0 × 10^–4

(c) 1.0 × 10^–5

(d) 2.0 × 10^–5

Ans. c

Sol.

Correct option is (c)

16. The normalisation constant 'A' for the wavefunction

(a)

(b)

(c)

(d)

Ans. a

Sol. For wave function, normalization constant 'A' can be calculated by applying normalization condition as

Correct option is (a)

17. The standard potential of a Daniel cell is +1.10 V and the equilibrium constant for the cell reaction is 1.5 × 10³⁷. It can be concluded that

(a) Zinc oxidises copper

(b) Displacement of copper by zinc goes to near completion

(c) Copper oxidises zinc

(d) Displacement of zinc by copper goes to completion.

Ans. b

Sol. As K_eq value is very large, so the cell reaction almost goes to completion.

Correct option is (b)

18. Which one of the following figures, showing kinetic energy of the ejected electron versus the frequency (v) of the incident photon, represents the Einstein's photoelectric effect?

(a)

(b)

(c)

(d)

Ans. a

Sol. Correct option is (a)

19. An aqueous solution containing 0.01 M FeCl₃ and 0.06 M HClO₄ has the same ionic strength as a solution of

(a) 0.09 M NaCl

(b) 0.04 M Na₂SO₄

(c) 0.06 M CuSO₄

(d) 0.03 M H₃PO₄

Ans. b

Sol.

Correct option is (b)

20. Which one of the following species is the conjugate base of HO^–?

(a) H₂O

(b) O^2–

(c) O₂^–

(d) O₃^2–

Ans. b

Sol.

Correct option is (b)

21. The solid-liquid phase diagram for the Mg-Zn system is shown in the figure below where the vertical line at X(Mg) = 0.33 represents the formation of a congruent melting compound MgZn₂. The figure is divided into seven regions depending upon the physical state of the system. The composition of the region #6 represents.

(a) Single phase of a solution of Mg and Zn

(b) Two phase region between the solid Zn and solid MgZn₂

(c) Two phase region between the liquid and solid MgZn₂

(d) Two phase region between solid Mg and solid MgZn₂

Ans. d

Sol.

Correct option is (d)

22. In the extraction of metals from their ores, which one of the following reduction methods can bring about a non-spontaneous reduction?

(a) Electrolytic reduction

(b) Reduction by carbon

(c) Reduction by another metal

(d) Reduction by hydrogen

Ans. b

Sol. Reduction by carbon because

Reduction of metal by method (a), (c) and (d), will depend on the reduction potential of metal, So, can not bring about a non-spontaneous reduction

In case of carbon reduction net of overall reaction (reduction of metal and oxidation of carbon) can be made –ve (i.e. spontaneous) at higher temperature because entropy change while oxidation of carbon is +ve, (because = so high negative value at high temperature)

Correct option is (b)

23. The correct order of the ionic radii is:

(a) ln³⁺ > Sn⁴⁺ > Sr²⁺ > Rb⁺

(b) Sn⁴⁺ > ln³⁺ > Sr²⁺ > Rb⁺

(c) Rb⁺ > ln³⁺ > Sr²⁺ > Sn⁴⁺

(d) Rb⁺ > Sr²⁺ > ln³⁺ > Sn⁴⁺

Ans. d

Sol. Rb, Sr, In, Sn all lie in the same period of periodic table. As charge on metal ion increases its size decreases.

Correct option is (d)

24. The correct valence shell electronic configuration of the element with atomic number 22 is

(a) [Ar]4s²3d²

(b) [Ar]3d⁴

(c) [Ar]3d²4s²

(d) [Ar]4s²4p²

Ans. c

Sol. Correct option is (c)

25. The ligand with only sigms bonding character is:

(a) CN^–

(b) CH₃^–

(c) CO

(d) NO

Ans. b

Sol. has only sigma bonds and lone pair in sp³ orbital, so this ligand has only -bonding character.

CN^–, CO and NO⁺ contains so it has and bonding orbital, it can have character.

Correct option is (b)

26. Which one of the following species is NOT isoelectronic with CO?

(a) N₂

(b) CN^–

(c) NO⁺

(d) O₂⁺

Ans. d

Sol. N₂, CN^– and NO⁺ all have 14 electrons, same as CO, but O₂⁺ has 15 electrons.

Correct option is (d)

27. During wittig reaction, a phosphorus yield gets converted to

(a) R₃P

(b) R₃P = 0

(c) R₃P⁺HOH^–

(d) R₂P – PR₂

Ans. b

Sol.

Correct option is (b)

28. Which of the following reactions does not give H₃PO₄?

(a)

(b)

(c)

(d)

Ans. b

Sol.

Correct option is (b)

29. The ionic radii of Ca²⁺ and F^– are 100 pm and 133 pm respectively. The coordination number of Ca²⁺ in the ionic solid will be

(a) 8

(b) 6

(c) 4

(d) 2

Ans. a

Sol.

As, according to radius ratio rule, if 0.732 <

Correct option is (a)

30. The shape of CH₃^– ion is:

(a) trigonal planar

(b) tetrahedral

(c) trigonal pyramidal

(d) linear

Ans. c

Sol.

Correct option is (c)

31. Identify reagent (P) and write the structure of products (Q, S and T) in the following

Identify the structures of the intermediate compounds Q, R and S. Show the transformation for each step.

Sol.

Syn hydroxylation of alkene followed by oxidation gives-dial compound 'Q'.

32. (a) For the following scheme of transformations, draw the structures of A, B, C and D.

(b) Complete hydrolysis of a pentapeptide with 6N HCl at 110ºC in a sealed tube gave 2 equivalents of glycine, one equivalent each of tyrosine, leucine and phenylalanine. Reaction of the pentapeptide with Sanger's reagent (2,4-dinitrofluorobenzene, DNFB) and subsequent hydrolysis gave the DNFB derivative of tyrosine. Chymotryspin cleavages of this peptide yielded tyrosine, leucine and a tripeptide. Deduce the sequence of the pentapeptide.

Sol. (a)

(b) Correct sequence of pentapeptide is

33. Complete the following reactions with appropriate structures for E, F, G, H and I.

Sol.

34. (a) Account fot the following transformation with an appropriate mechanism. Give the structure of the Hoffmann exhaustive methylation product of 1, 2-dihydro derivative of [X].

(b) The optically pure ester [J] is hydrolysed in aqueous acetic acid to form a racemic mixture of cis-4, 4-dimethyl-2-acetoxycyclopentanol [K]. Give a mechanistic explanation to account for the formation of [K] and the observed change in the optical activity.

Sol. (a) First step is similar to Beckmann rearrangement in which migration of group takes place from C to N. Second step is intramolecular electrophilic aromatic substitution reaction

As (I) and (II) are enantiomers, and they are formed in 1:1 ratio, So, it forms a recemic mixture, so 'K' is optically inactive.

35. (a) M is a first row transition metal. MCl₂ on treatment with aqueous ammonia gives a blue coloured solution of complex N. A solution of MCl₂ also gives a bright red precipitate of complex O with ethanoic dimethylglyoxime.

(i) Identify M and draw the structure of O.

(ii) Determine the hybridisation of M in complex N.

(iii) Identify the paramagnetic complex.

(b) [Cr(H₂O)₆]³⁺ gave an absorption at 208 kJ/mol which corresponds to Calculate the crystal field stabilisation energy of this complex in kJ/mol.

Sol. (a)

(iii) N [Ni(NH₃)₆]Cl₂ is paramagnetic complex, because it has '2' unpaired electrons in its 3d orbital.

36. (a) Consider the ethers H₃SiOSiH₃ and H₃COCH₃.

(i) Which ether has more lewis base character?

(ii) Which angle [Si-O-Si and C-O-C] is greater? Justify your answer.

(b) Starting from SiO₂, show how the following polymer is prepared industrially?

Sol. (a) (i) H₃COCH₃ has more Lewis base character.

Lone pair of oxygen in (I) is delocalized in vacant d orbital of silicon via back bonding, so l.p. on oxygen is not available. But in case of dimethyl ether ((CH₃)₂O), oxygen l.p. is available, so it can act as stronger lewis base.

(ii) Due to back bonding in (SiH₃)₂O, double bond character arises (as shown in canonical structure II and III above), which leads to greater bond pair-bond pair repulsion, so Si–O–Si bond angle is larger w.r.t. C–O–C angle where bonds have single bond character only.

(b) Pure Si is produced from reduction of SiO₂ in an electric furnance in presence of coke.

(CH₃)₂SiCl₂ on hydrolysis gives silicon polymer.

 

37. (a) A solution of metal ion (M²⁺) when treated with H₂S gas gives a black precipitate A. Precipitate A dissolved in hot concentrated nitric acid to give B along with elemental sulfur. The metal ion solution also gives a white precipitate C with an excess of KI. Write the chemical formulae of A, B and C

(b) Why are potassium permanganate solutions unstable in the presence of Mn²⁺ ions? In the quantitative estimation of iron present in iron ores dissolved in dilute HCl, titrations with dichromate are preferred over titrations with permanganate. Rationalise.

Sol.

(b) Mn⁺² catalyses the decomposition of KMnO₄, as KMnO₄ oxidises Mn⁺² and itself gets reduced.

Also KMnO₄ is not a primary standard, because it undergoes decomposition in water solution,

So, KMnO₄ solution is not suitable for estimation of Fe dissolved in HCl.

But K₂Cr₂O₇ solution can be used as a primary standard, because it is stable in aqueous medium, thats why it is prefered over KMnO₄ solution.

38. (a) Al₂Cl₆ and Al₂Me₆ are dimeric in gas phase. Draw their structures. Which compound has more Lewis acid character? Explain.

(b) Arrange the halides SnCl₂, PbCl₂, SiCl₂ in increasing order of their stability. Give reasons for your answer.

Sol.

Al₂(CH₃)₆ is more lewis acidic in character, as bridging Al–C–Al bonds are 3-center-2-electron bonds, so, Al has incomplete octet, but in Al₂Cl₆ all bonds are 2-centere-2-electron bonds. So has complete octet, so less tendency to accept electron-pair (i.e. less lewis acidic character).

(b) Stability order

Si, Sn and Pb belong to group 14 and each one of them has ns² np² configuration, but due to inert pair effect, as we go down the group ns² electron gets inert, and shows reluctancy towards removal.

So, stability of +2 oxidation state is,

As, Si⁺² < Sn⁺² < Pb⁺², but +4 o.s. stability is as, Si⁺⁴ > Sn⁺⁴ > Pb⁺⁴

So, stability order in MCl₂ salt is, SiCl₂ < SnCl₂ < PbCl₂

39. (a) Acdification of an aqueous solution of yellow sodium chromate gives an orange coloured A. A compound solution of A on treatment with concentrated H₂SO₄ gives a bright orange solid B. Compound A in the presence of concentrated H₂SO₄ reacts with anion C to give a deep red coloured liquid. Identify A, B and C.

(b) undergoes an emission to give element X followed by a emission to give element Y.

(i) Write the valence shell electronic configuration of Y.

(ii) Indicate the groups of the periodic table to which X and Y belong.

Sol.

(i) Valence shell electronic configuration of Y is, 6s² 6p³

(ii) X belongs to group 14 (carbon group)

Y belongs to group 15 (Nitrogen group)

40. (a) When an ideal monoatomic gas is expanded from 1.5 bar, 24.8 L and 298 K into an evacuated container, the final volume becomes 49.6 L. Calculate for the process.

(b) The Maxwell distribution function for the distribution of speeds of molecules in gaseous systems is given by

Sol.

41. (a) At 600 K and 200 bar, a 1:3 (molar ratio) mixture of A₂ and B₂ react to form an equilibrium mixture containing Assuming ideal gas behaviour, calculate K_p for the reaction

(b) A 50 mL 0.05 M solution of Fe(II) is titrated with 0.05 M solution of Ce(IV) in the presence of dilute H₂SO₄ at 25ºC. Calculate the equivalence point potential and the equilibrium constant K in terms of log K

Sol. (a) Initial mole ratio of A₂ and B₂ is 1 : 3

At equivalent point,

For reaching equivalence point 50 ml of 0.05 m Ce(IV) solution is being used,

42. (a) The vapour pressure of D₂O at 20ºC is 745 mm Hg. When 15 g of a non-volatile compound is dissolved in 200 g of D₂O the pressure changes to 730 mm Hg. Assuming the applicability of Raoult's law, calculate the molecular weight of the compound.

(b) An enzyme following Michaelis-Menten kinetics was found to have highest activity at 37ºC and pH 7.0. If the maximum velocity V_max for this enzyme was 2.4 × 10^–4 mol L^–1 s^–1 with an initial enzyme concentration [E]₀ = 2.4 nM, calculate the turnover frequency.

Sol.

From Raoult's law,

Relative lowering of vapour pressure = (Mole fraction of non volatile solute)

V_max = maximum rate of reaction = k₂[E]₀ = 2.4 × 10^–4 ms^–1 and [E]₀ = 2.4 × 10^–9 M

43. (a) Consider the 4π electrons in cyclobutadiene to be free particles in a 2-dimensional square box of length 2Å. Calculate the wavelength of the electronic transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). Also write down the normalised wavefunctions for the occupied degenerate states.

(b) The reaction

is first order in both directions. At 25ºC, the equilibrium constant (K) of this reaction is 0.40. If 0.115 mol dm^–3 of cis-isomer is allowed to equilibrate, calculate the equilibrium concentration of each isomer.

Sol.

Normalized wave function for HOMO are:

44. (a) With i, j and k as the unit vectors along, X, Y, Z axes, express the vector, in the given figure in terms of the coordinate of P₁ and P₂. Also determine the dot products of the unit vectors, i, j, k.

(b) Deduce whether the matrices A and B commute or not.

Sol.