1. After the following interchanging of groups in the Fischer projection of 2-bromobutane, the configuration of (X) and (Y) will be

(a) X = R, Y = S

(b) X = R, Y = R

(c) X = S, Y = R

(d) X = S; Y = S

Ans. c

Sol.

Correct option is (c)

2. The major product of the reaction

(a)

(b)

(c)

(d)

Ans. c

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

Correct option is (c)

3. In the reaction sequence,

The product (Y) is

(a) CH₃COCH₂COOCH₃

(b) CH₃COCH(CH₃)₂

(c)

(d) CH₃COC₂H₅

Ans. c

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

Correct option is (c)

4. The major product (X) in the reaction

(a)

(b)

(c)

(d)

Ans. b

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

Correct option is (b)

5. The product of the reaction

gives positive test with Fehling's solution. The product is

(a) C₆H₅OH

(b) C₆H₄ (Cl) CHO

(c) C₆H₄ (OH)CHO

(d) C₆H₅CHO

Ans. d

Sol.

Correct option is (d)

6. The compound (X) in the reaction sequence

(a)

(b)

(c)

(d)

Ans. a

Sol. Correct option is (a)

7. The major product of the reaction

(a)

(b)

(c)

(d)

Ans. a

Sol. This reaction is an examples of Pinacol – Pinacolone rearrangement be shown stepwise as

Correct option is (a)

8. The increasing order of the acidity of the hydrogen marked in bold italics among the following is:

(a) III < II < I

(b) II < I < III

(c) I < II < III

(d) II < III < I

Ans. d

Sol.

Resonance energy of conjugate base of I, II and III has order. I > III > II

Resonance energy is proportional to stability of compound (strong acid has stable conjugate base).

III is less aromatic than I due to annulation effect.

Correct option is (d)

9. The major product of the reaction

is

(a)

(b)

(c)

(d)

Ans. c

Sol. In the above reaction, 1, 4 addition of H-Br takes place such that formation of most stable alkene is obtained in major extent.

Correct option is (c)

10. The number of enantiomers of camphor

(a) Four

(b) Two

(c) Three

(d) One

Ans. d

Sol.

Each bridgehead C is a chiral centre. Camphor, with two different chiral carbon must be expected to have 2ⁿ or four stereoisomers existing as two racemic forms but only only is known, because, the bridge carbon stereocentre cannot be inverted.

Correct option is (d)

11. The decreasing order of the first ionization energy of the following element is

(a) He > H > Be > B

(b) Be > B > H > He

(c) H > He > Be > B

(d) B > Be > He > H

Ans. a

Sol.

Here He and Be has more IE than corresponding H and B due to the completly filled 1s and 2s subshell.

Correct option is (a)

12. If the values of Madelung constants of the following compounds are equal, then their lattice energy values decreases in the order

(a) KCl > NaF > CaO > Al₂O₃

(b) Al₂O₃ > CaO > NaF > KCl

(c) NaF > KCl > CaO > Al₂O₃

(d) Al₂O₃ > CaO > KCl > NaF

Ans. b

Sol.

Where, M = Madelung constant

r = distance between cation and anion-center

So, depending upon charge and distance correct order is (b)

Correct option is (b)

13. The fluoride, whose value of dipole moment is not equal to zero, is

(a) XeF₄

(b) CF₄

(c) SF₄

(d) PF₅

Ans. c

Sol. SF₄ has not zero dipole moment due to its unsymmetrical see-saw structure.

Correct option is (c)

14. The decreasing order of ionic nature of the following compound is:

(a) Lil > NaBr > KCl > CsF

(b) Lil > KCl > NaBr > CsF

(c) CsF > NaBr > KCl > Lil

(d) CsF > KCl > NaBr > Lil

Ans. d

Sol. According to Fajan's rule, if cation is large and anion is small, then ionic character is higher. So, correct order is represented by (d)

Correct option is (d)

15. The atomicity and the total number of bonds in the elemental white phosphorous molecule are respectively

(a) 4 and 6

(b) 6 and 4

(c) 4 and 4

(d) 6 and 6

Ans. a

Sol. White phosphorous (P₄)

Total Bonds = 6

Correct option is (a)

16. The octahedral crystal field splitting of d orbital energies of the following metal ions decrease in the order

(a) Co²⁺ > Co³⁺ > Rh³⁺

(b) Rh³⁺ > Co³⁺ > Co²⁺

(c) Rh³⁺ > Co²⁺ > Co³⁺

(d) Co³⁺ > Co²⁺ > Rh³⁺

Ans. b

Sol. Higher the charge on central metal ion, higher will be CFSE.

As we go down the group of metal ion CFSE increases.

Correct option is (b)

17. The half-life of a radioactive nuclide is 20 years. If a sample of this nuclide has an activity of 6400 disintegrations per minute (dis/min) today, its activity (dis/min) after 100 years would be

(a) 850

(b) 1600

(c) 200

(d) 400

Ans. c

Sol. For the given radioactive nuclide

t_1/2 = 20 years, Initial activity (A₀) = = 6400 dis/min

t = 100 years, = 5t_1/2 Final activity (A_t) = ?

Correct option is (c)

18. The average value of C-C bond in graphite is:

(a) 1

(b) 3/2

(c) 3/4

(d) 4/3

Ans. d

Sol. In graphite all carbon are sp² hybridized and 1-electron lies in p-orbital of all carbon atoms which are delocalized such that there is partial double bond character, such that bond order is

OR

Correct option is (d)

19. The optical absorption spectrum of [Ti(H₂O)₆]³⁺ has its absorption maximum at 20300 cm^–1. The magnitude of crystal field stabilization energy in cm^–1 is

(a) 8120

(b) 16240

(c) 24360

(d) 50750

Ans. a

Sol.

Correct option is (a)

20. In inorganic qualitative analysis, H₂S in acidic medium will Not precipitate

(a) HgS

(b) ZnS

(c) CuS

(d) CdS

Ans. b

Sol. As ZnS has higher solubility product than HgS, CuS and CdS, So H₂S in acidic medium do not provide enough S^2– to precipitate ZnS.

Correct option is (b)

21. The phase diagram of a pure substance is sketched below.

The number of degrees of freedom at points P1, P2 and P3, respectively are

(a) 2, 1, 0

(b) 1, 2, 0

(c) 2, 0, 1

(d) 0, 2, 1

Ans. a

Sol. At Pl, F (degree of freedom) = C – P + 2 = 1 – 1 + 2 = 2

At P2, F (degree of freedom) = C – P + 2 = 1 – 2 + 2 = 1

At P3 (triple point), F (degree of freedom) = C – P + 2 = 1 – 3 + 2 = 0

Correct option is (a)

22. The solubility products (K_sp) for three salts MX, MY₂ and MZ₃ are 1 × 10^–8, 4 × 10^–9 and 27 × 10^–8, respectively. The solubility of these salts follows the order

(a) MX > MY₂ > MZ₃

(b) MZ₃ > MY₂ > MX

(c) MZ₃ > MX > MY₂

(d) MY₂ > MX > MZ₃

Ans. b

Sol.

Correct option is (b)

23. The temperature (T) dependence of the equilibrium constant (K) of a chemical reaction is correctly described by the following statement:

(a) For an endothermic reaction, the slope of ln K vs 1/T plot is positive.

(b) For an exothermic reaction, K is proportional to T

(c) For an exothermic reaction, K at a higher temperature is lower than K at a lower temperature

(d) If is independent of temperature, the change in K with T is smaller at lower temperatures.

Ans. c

Sol. From Van't hoff equation

Correct option is (c)

24. When the concentration of K⁺ across a cell membrane drops from 0.01 M to 0.001 M, the potential difference across the membrane is:

(a) 0.0 V

(b) 0.0059V

(c) 0.059 V

(d) 0.59 V

Ans. c

Sol.

Correct option is (c)

25. The statement that is correct for both electrochemical (galvanic) cells and electrolytic cell is :

(a)

(b) Free energy decreases in both cells

(c) The cell potential are temperature independent

(d) Chemical energy is converted into electrical energy in both cells

Ans. a

Sol. Only statement (a) is correct

Free energy decreases only in case of galvanic cells

In case of electrolytic cells, a non spontaneous redox takes place

26. The molar heat capacity at constant volume of a colourless gas is found to be 25 J mol^–1 K^–1 at room temperature. The gas must be

(a) N₂

(b) O₂

(c) CO₂

(d) SO₂

Ans. d

Sol.

Degree of freedom (f) = 6

Which is only possible for any non-linear molecule (SO₂). (Neglecting vibrational degree of freedom as at room temperature)

Correct option is (d)

27. The wavelength for a particle (moving in a ring) is where is the polar angle. The probability of finding the particle in a small interval when the value of is

(a)

(b)

(c)

(d)

Ans. b

Sol.

Correct option is (b)

28. An electric current of 0.965 ampere is passed for 2000 seconds through a solution containing [Cu(CH₃CN)₄]⁺ and metallic copper is deposited at the cathode. The amount of Cu deposited is

(a) 0.005 mol

(b) 0.01 mol

(c) 0.02 mol

(d) 0.04 mol

Ans. c

Sol. W = Z.I.t

Correct option is (c)

29. The Maxwell-Boltzmann distribution for molecular speeds is shown in the following figure.

In the figure, H is the height of the peak, L is the location of the maximum and W is the width at half height. As the temperature is decreased,

(a) H increases, L decreases and W increases

(b) H increases, L decreases and W decreases

(c) H decreases, L decreases and W increases

(d) H decreases, L decreases and W decreases

Ans. b

Sol. Correct option is (b)

30. A system undergoes two cyclic processes 1 and 2. Process 1 is reversible and process 2 is irreversible. The correct statement relating to the two processes is

(a)

(b) q_cycle = 0 for process 1 and q_cycle 0 for process 2

(c) More heat can be converted to work in process 1 than in process 2

(d) More work can be converted to heat in process 1 than in process 2

Ans. b

Sol.

So for reversible process, q_cycle = 0 and for irreversible process, q_cycle < 0.

Correct option is (b)

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

Sol.

32. For the reaction

(a) what is the optical activity of the product ?

(b) draw the energy profile for the reaction

(c) wrtie the structure of the intermediate

(d) what is the effect of doubling the concentration of KOH in the rate of the products?

(e) If aqueous KOH is replaced by alcoholic KOH. Write the structure of the products formed.

Sol. (i) Since in aqueous medium reaction proceeds through SN¹ mechanism. Therefore, product is optically inactive and racemic mixture will be formed.

(ii)

(iv) Since reaction proceeds through S_N1 mechanism. Therefore, rate of reaction will remain unaffected, w.r.t. to change in KOH concentration,

(b) In presence of alcoholic KOH reaction will undergo elimination reaction.

33. (a) Suggest a method for the following transformation involving minimum number of steps

Indicate the reagents/reaction conditions required at each step clearly.

(b) A dipeptide on hydrolysis gives two amino acids (X) and (Y). If the dipeptide is first treated with HNO₂ and then hydrolysis is carried out, (X) and lactic acid are obtained. (X) on heating gives 2, 5-diketopiperazine as shown below. Identify (X) and (Y), and write their sequence in the dipeptide.

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

34. Identify the compounds A, B, C, D and E in the following reactions.

Sol.

35. (a) Why do the boiling points of the following compounds vary in order,

H₂O > H₂Se > H₂S?

(b) Identify the products in the reaction of CCl₄ and SiCl₄ with water. Justify your answer.

Sol. (a) Higher the force of interaction between molecules, higher the energy (or temperature) will be required to boil the molecule.

H₂O contains intermolecular H-bonding but H₂S and H₂Se have vander waals force of interaction. As H-bond strength > vander waals force of interaction.

H₂O has highest b.p. (H₂O is liq. at room temperature)

But vander waals force molecular wt.

H₂Se will have higher b.p. than H₂S (both are gas at room temperature)

So, The b.p. order is,

H₂O > H₂Se > H₂S

CCl₄ is inert towards its reaction with H₂O, because carbon is unable to expand its valency due to lack of d-orbital in 2^nd period.

But SiCl₄ is extremely reactive with H₂O, because Si can expand its octed/valency due to presence of 3d orbital as shown below.

Due to smaller size of carbon and four chlorine group crowdly attached on carbon atom. So, hydroxyl group cann't group on carbon centre in S_N2 manner.

36. (a) Write the steps involved in the production of pure elemental silicon from silica.

(b) Both the products A and B in the following reactions, contain boron and nitrogen. identify A and B

Sol. (a) Production of elemental silicon from silica involves these steps:

(i) Reducing SiO₂ with high purity coke

(ii) Converting Si to SiCl₄ and purifying this SiCl₄ by distillation,

(iii) Reduction of SiCl₄ by Mg or Zn.

Ultra pure Si can be made from above obtained Si via Zone refining.

37. (a) Addition of potassium oxalate solution to a hot solution of potassium dichromate containing dilute sulfuric acid leads to effervescence and formation of potassium trisoxalatochromate (III).

(i) Write the chemical formula of the chromium complex formed.

(ii) Write the balanced chemical formula for the formation of the complex.

(iii) Calculate the room temperature spin-only magnetic moment, in Bohr magnetons, of the complex.

(b) Write the structure of possible isomers of [CoCl₂(en)₂]Cl.

Sol. (a) (i) Chromium complex K₃[Cr(Ox)₃]

(ii) In complex, K₃[Cr(Ox)₃], Cr⁺³ has 3d³ electrons in its t_2g orbital.

Number of unpaired electron (n) = 3

Spin only magnetic moment

38. (a) Draw the unit cell of CsCl lattice. Draw the (100) and (110) places separately and indicate the position of ceasium and chloride ions.

(b) The hydration enthalpies of divalent metal ions of ten elements from calcium to zinc are plotted against their atomic numbers. Why do the hydration enthalpies of only three elements, Ca, Mn and Zn fall on a straight line, whereas values for other metal ions deviate from this line?

Sol.

(b) Hydration of metal ions (M⁺²) produces an enthalpy change that is commensurate with the size, charge of the ion and crystal field stabilisation energy (CFSE).

So, shows non-linear variation if C.F.S.E. 0. If CFSE = 0 (i.e. for Ca, Mn and Zn which has d⁰, d⁵ and d¹⁰ configuration respectively), then it lies on the straight line.

39. (a) 5 grams of a protein was hydrolysed into amino acids, one of which is alanine. To this mixture, 0.1 gram of partially deutrated alanine, H₂N-CH(CD₃)-COOH, was added. After thorough mixing, some of the alanine was separated and purified by crystallization. The crystalline alanine contains 0.652 weight percent of D. How many grams of alanine were originally present in 5 grams of protein?

(b) What is the role of ammoniacal buffer in the volumetric titration of zinc sulphate against EDTA, using Solochrome black (Eriochrome black T) indicator? Write the structure of Zn-EDTA anionic complex.

Sol. (a) Let x gm of alanine is present in 5 gm of protein.

(b) Ammonical buffer maintains the pH such that the solution remains basic enough to deprotonate all the 4-carboxylic hydrogens of EDTA, so that it can bind effectively to Zn⁺².

40. (a) Calculate the pH of a solution obtained by mixing 50.00 mL of 0.20 M weak acid HA (K_a = 10^–5) and 50.00 mL of 0.20 M NaOH at room temperature.

(b) One mole of a salt of type MX is dissolved in 1.00 kg of water. The freezing point of the solution is –2.4°C. Calculate the percent dissociation of the salt in water.

Sol.

Now this weak acid salt will undergo hydrolysis.

41. (a) The rate constant of the reaction ClO + NO Cl + NO₂ varies with temperature as :

Determine the Arrhenius activation energy for the reaction, assuming that the frequency factor does not change in this temperature range.

(b) Ozone seems to be formed in the atmosphere through the photolysis of diatomic molecule :

Applying steady-state approximation, determine the rate law for the formation of ozone. Show that the formation of ozone follows first order kinetics when the concentration of O₃ is extremely small.

Sol. (a) We have

Where k₂ and k₁ are rate constant for the reaction at temperature T₁(K) and T₂(K) respectively.

Give, k₂ = 1.0 × 10^–11 and k₁ = 2.0 × 10^–11

T₂ = 400 K and T₁ = 200 K

So from equation (1),

= –2.304 kJ/mole

(b) For the reaction

As 'O' is an intermediate, So, applying S.S.A on 'O'.

Substituting [O] from equation (2) in equation (1),

42. (a) The reaction is carried out at 300 K by mixing N₂ and H₂. The standard free energy of formation of NH₃ is –16.4 kJ/mol. After one hour of mixing, the partial pressures of N₂, H₂ and NH₃ are 50 bars, 2 bars and 200 bars, respectively. What is the reaction free energy at this stage of the reaction?

b) Plot schematically the concentration dependence of molar conductivity of a strong electrolyte and a weak electrolyte in the same figure. The limiting ionic molar conductivities of K⁺ and Cl^– are 73.5 and 76.5 S cm² mol^–1, respectively. If the molar conductivity of 0.1 M KCl solution is 130.0 S cm² mol^–1, calculate the Kohlrausch's constant for KCl solution.

Sol.

At constant temperature for the above reaction can be written as,

= –16400+8.31× 300 × 2.303 log [100] = –16400 + 8.31 × 300 × 2.303 log 2

= –14672.3 J/mole = 14.67 × 10³ J/mole = –14.67 kJ mole

Kohlrausch law for variation of with concentration (c).

43. (a) The electronic wavefunction for hydrogen atom in the 2s state is given as

Determine the most probable radial distance for the electron in this state and also the position of the node (in terms of a₀)

(b) Calculate the wavelength corresponding to the lowest energy excitation of an electron confined to a one-dimensional box of length 1 nm. (Energy levels for a particle in a one dimensional box are given by E_n = n²h²/8ma²).

Sol.

As is function of 'r' only, so probability of finding electron at distance 'r' is given by

But r cannot be '0' and because at nucleus and at infinite distance P(r) = 0

For P(r) to be maximum at any of the above values it must satisfy,

(b) Let be the wavelength of wave required to exite electron from ground state to 1st exited state.

44. (a) Solve the differential equation y´´ = 5y´ + 6y = 0 with the initial conditions y(0) = –1 and y´(0) = 0. Here y´ and y´´ refer to the first and the second derivatives, respectively, of y with respect to x. Verify your answer.

(b) For a particle with position and momentum in m and kgmS^–1, respectively, calculate the magnitude of the angular momentum L=r×p.

Sol. (a) Given y´´ – 5y´ + 6y = 0; y(0) = –1 and y´(0) = 0