GATE Chemistry 2019
Previous Year Question Paper with Solution.

1. Consider a two-state system at thermal equilibrium having energies 0 and 2kBT for which the degenracies are 1 and 2, respectively. The value of the partition function at the same absolute temperature T is _________. (Round off to two decimal places)

(kB is the Boltzmann constant)

Ans. 1.27

Sol.

= 1 + 2e–2

q = 1.27

2. In Freundlich isotherm, a linear relationship is obtained in the plot of ( = surface coverage and p = partial pressure of the gas)

(a) vs p

(b) ln () vs ln (p)

(c) ln () vs p

(d) vs ln(p)

Ans. (b)

Sol. = K(P)1/n According to treundlich's isotherm

ln = ln K +

y = C + mx

Option B is correct.

3. The value of [Ni(H2O)6]2+ is 8500 cm–1. The values for [NiCl6]4– and [Ni(NH3)6]2+ compared to [Ni(H2O)6]2+ are

(a) higher and lower, respectively

(b) lower and higher, respectively

(c) higher in both complex ions

(d) lower in both complex ions.

Ans. (b)

Sol. Value of µ ligand field strength

Correct option is (b)

4. Among the following carbon allotropes, the one with discrete molecular structure is

(a) Diamond

(b) -Graphite

(c) -Graphite

(d) Fullerene

Ans. (d)

Sol. Fullerene exists in discrete molecular structure among the allotropes of carbon whereas diamond and graphite have a conditions network structure.

Correct option is (d)

5. Micelle formation is accompanied by the

(a) decrease in overall entropy due to ordering

(b) increase in overall entropy mostly due to increase in solvent entropy

(c) increase in overall entropy mostly due to increase in solute entropy

(d) increase in overall entropy and decrease in enthalpy

Ans. (b)

Sol. During Micelle formation , hydrophobic part of soap releases water ( solvent ) so solvent entropy increases and thus overall entropy increases.

6. The entropy change for the melting of 'x' moles of ice (heat of fusion is 80 cal g–1) at 273 K and 1 atm pressure is 28.80 cal K–1. The value of 'x' is _______ (Round off to two decimal places)

(Molecucular weight of water = 18 g/mol)

Ans. 5.46

Sol. For 1 mol 18g ice

For x mol 18 × x

x = 5.46

7. Among the following compounds, the number of compounds that DO NOT exhibit optical activity at room temperature is __________.

Ans. 4

Sol. Has a chiral centre and is optically active has no POs.

Has a chiral centre and is optically active have no POs.

Rest all the structures are optically inactive

So total (4) structures are optically inactive

Correct answer is 4.

8. The INCORRECT statement about the interhalogen compound ICl3 is

(a) It exists as a dimer

(b) Geometry around the iodine is tetrahedral in solid-state

(c) It decomposes as ICl and Cl2 in gas-phase

(d) Liquid ICl3 conducts electricity

Ans. (c)

Sol. In solid form ICl3 exist as dimer but in gaseous form exist as ICl3.

I2Cl6

Correct option is (c)

9. The major product formed in the following reaction is

(a)

(b)

(c)

(d)

Ans. (b)

Sol.

10. On heating a sample of 25 mg hydrated compound (molecular weight = 250 g/mol) in thermogravimetric analysis, 16 mg of dehydrated compound remains. The number of water molecules lost per molecule of hydrated compound is ___________.

(Molecular weight of water = 18 g/mol)

Ans. 5

Sol. Sample weight = 25 mg No. of moles =

After dehydration = 16 mg

Amount of H2O = 25 – 16 = 9 mg

Moles of H2O =

No. of moles lost per molecule is 5.

11. The Incorrect statement about the solid-state structure of CsCl and CaF2 is:

(a) Cations in both solids exhibit coordination number 8.

(b) CsCl has bcc type structure and CaF2 has cubic close pack structure

(c) Radius ratio for Cs/Cl and Ca/F is 0.93 and 0.73, respectively

(d) Both exhibit close pack structure

Ans. (b, d)

Sol.

Generally, people consider it as BCC/since they assume that atoms/ion are at 8 corner and at Body center. But this is not true.

CsCl has SCC or primitive lattice with Cs+ at cubical void.

This is proved by structure factor concept.

12. Gas phase bond length and dipole moment of a compound (MX) is 3Å and 10.8 D, respectively. The ionic character in gas phase MX is _________% (Round off to one decimal place)

(1D = 3.336 × 10–30 C m)

Ans. 75

Sol. d = 3Å µobs = 10.8 D.

d = 3 × 10–8 cm

µcal = a × d (1 unit charge = 4.8 × 10–10)

= 4.8 × 10–10 esu × 10–8 × 3 cm

= 14.4 × 10–18 esu cm

µcal = 14.4 D

% I.C. =

13. The major product formed in the following reaction is

(a)

(b)

(c)

(d)

Ans. (b)

Sol.

Correct option is (b)

14. The INCORRECT statement about the silicones is

(a) They are thermally unstable because of the Si-C bond.

(b) They are insoluble in water.

(c) They are organosilicon polymers

(d) They have stable silica-like skeleton (–Si–O–Si–O–Si–)

Ans. (a)

Sol. Option a is incorrect as Si–C bond is thermally stable

Correct option is (a)

15. In a 400 MHz 1H NMR spectrometer, a proton resonates at 1560 Hz higher than that of tetramethylsilane. The chemical shift value of this proton is ________ppm. (Round off to one decimal place)

(Chemical shift of tetramethylsilane is fixed at zero ppm)

Ans. 3.9

Sol.

Correct answer is (3.9)

16. Consider a system of three identical and distinguishable non-interacting particles and three available nondegenerate single particle energy levels having energies 0, and 2. The system is in contact with a heat bath of temperature T K. A total energy of 2 is shared by these three particles. The number of ways the particles can be distributed is ______

Ans. 6

Sol.

Total ways, W = W1 + W2

W = 3 + 3 = 6

17. The product(s) formed in the following reaction is(are)

(a) I only

(b) II only

(c) II only

(d) Mixture of I and II

Ans. **

Sol.

18. The total number of and particles emitted in the following radioactive decay is _____

Ans. 11

Sol.

Equating mass No.

238 = 210 + 4x + 0 (y)

x = 7

Equating Atomic No.

92 = 82 + 2x – y

y = 4

x + y = 7 + 4 = 11

19. The number of following diene(s) that undergo Diels-Alder reaction with methyl acrylate is ____

Ans. 5

Sol.

Correct answer is 5.

20. An ideal gas occupies an unknown volume V liters (L) at a pressure of 12 atm. The gas is expanded isothermally against a constant external pressure of 2 atm so that its final volume become 3L. The work involved for this expansion process is _______cal. (Round off to two decimal places)

(Gas constant R = 0.082 L atm mol–1 K–1 = 2 cal mol–1 K–1)

Ans. –121.95

Sol. P1 = 12 atm, V1 = V

P2 = 2 atm, V2 = 3L P1V1 = P2V2

W = –P2 (V2 – V1) 12V = 3 × 2

= –121.95 Ca L

21. The number of 1H NMR signals observed for the following compound is________

Ans. 6

Sol.

No. of signals = 6

e & f diasteriotopic protons have different signals.

Correct answer is (6)

22. In the following reaction, the stereochemistry of the major product is predicted by the

(a) Cram's model

(b) Cram's chelation model

(c) Felkin model

(d) Felkin-Anh model

Ans. **

Sol.

23. The number of CO stretching bands in IR spectrum of trigonal bipyramidal cis-M(CO)3L2 is _____

(M = metal and L = monodentate ligand)

Ans. 3

Sol.

cis-[M(CO)3L2] TBP complex will have 2 different type of CO ligands and hence it will show 3 different peak in IR spectra

Correct answer is 3.

24. Consider the following phase diagram of CO2 (not to scale). At equilibrium, the INCORRECT statement is:

(a) At 200 K, on increasing the pressure from 1 to 50 atm, CO2 gas condenses to liquid

(b) It is not possible to obtain liquid CO2 from gaseous CO2 below 5.11 atm

(c) Both liquid and gas phase of CO2 coexist at 298.15 K and 67 atm.

(d) With increasing pressure, the melting point of solid CO2 increases.

Ans. (a)

Sol. (a) is incorrect

At 200 K, along sublimation curve, solid gas.

On increasing pressure, CO2 gas gets converted to solid.

25. The Woodward-Hoffmann condition to bring out the following transformation is

(a) conrotatory

(b) disrotatory

(c) , disrotatory

(d) , conrotatory

Ans. (d)

Sol.

26. The major product formed in the following reaction is

(a)

(b)

(c)

(d)

Ans. **

Sol.

27. The major product formed in the following reaction is

(PCC = pyridinium chlorochromate)

(a)

(b)

(c)

(d)

Ans. **

Sol.

28. Suppose the wave function of a one dimensional system is

In an experiment measuring the momentum of the system, one of the expected outcomes is

(a) 0

(b)

(c)

(d)

Ans. (d)

Sol.

29. The experimentally observed magnetic moment value, which match well with the spin-only values for the pair of aqueous ions is

(Atomic number: Cr = 24, Co = 27, Gd = 64, Tb = 65, Dy = 66 and Lu = 71)

(a) Cr(III) and Gd(III)

(b) Co(II) and Gd(III)

(c) Cr(III) and Dy(III)

(d) Lu(III) and Tb(III)

Ans. (a)

Sol. Cr(III) and Gd(III) both have observed same with the spin-only values for the pair of aqueous ions.

Correct option is (a)

30. Consider the following equilibrium

At 298 K, the standard molar Gibbs energies of formation, of SO2(g) and SO3(g) are –300 and –371 kJ mol–1 espectively. The value of the equilibrium constant, KP at this temperature is _____× 1010. (Round off to the nearest integer)

(Gas constant R = 8.31 J mol–1 K–1)

Ans. 275 × 1010

Sol.

= –71 kJ mol–1

–71000 = –8.31 × 298 ln Kp

ln Kp = 28.67

Kp = 2.75 × 1012 = 275 × 1010

Correct answer is 275 × 1010.

31. The major product formed in the following reaction is

(a)

(b)

(c)

(d)

Ans. **

Sol.

If heat is not given then also [3,3] sigmatropic.

32. In the EPR spectrum of a methyl radical, the number of the lines and their relative intensities, respectively, are

(a) 1 and 1

(b) 3 and 1 : 2 : 1

(c) 4 and 1 : 2 : 2 : 1

(d) 4 and 1 : 3 : 3 : 1

Ans. (d)

Sol. 3 equivalent proton coupling with radical.

(n + 1) = (3 + 1) = 4 peaks with intensity according to pascal triangle.

Intensity 1 : 3 : 3 : 1

Correct answer is (d)

33. The specific rotation of optically pure (R)-2-bromobutane is –112.00. A given sample of 2-bromobutne exhibited a specific rotation of –82.88. The percentage of (S)-(+)-enantiomer present in this sample is ______

Ans.

Sol.

Let conc. of the sol. is 1

Let conc. of the R 2-bromobutane is (x)

then conc. of the S 2-bromobutane is (1 – x)

–82.88 × 1 = –112 × x + 112 (1 – x)

–82.88 = –224x + 112

–194.88 = –224x

x =

% of R-2 bromobutane is 87%

% of S-2 bromobutane is 13%

34. A complex is composed of one chromium ion, three bromides and six water molecules. Upon addition of excess AgNO3, 1.0 g aqueous solution of the complex gave 0.94 g of AgBr. The molecular formula of the complex is

(Atomic weight: Cr = 52, Br = 80, Ag = 108, O = 16 and H = 1)

(a) [Cr(H2O)6]Br3

(b) [Cr(H2O)5Br]Br2·H2O

(c) [Cr(H2O)4Br2]Br·2H2O

(d) [Cr(H2O)3Br3]·3H2O

Ans. (b)

Sol. Molecular mass of Cr(Br)3 · 6H2O of the complex = 400g, molecular mass of AgBr = 188 g

1g of complex 0.94g of AgBr

400g of complex (0.94 × 400)g AgBr = 376g AgBr

No. of mole of

So, 1 mole of complex give 2 mole of AgBr.

Hence M.F of complex must be [Cr(H2O)5Br]Br2·H2O

Correct option is (b)

35. Following are the examples of silicate minerals

(I) Zircon, ZrSiO4

(II) Beryl, Be3Al2Si6O18

(III) Pyrophyllite, Al2(OH)2[(Si2O5)2]

The correct structural description of the minerals is

(a) I–ortho silicate, II–Cyclic silicate and III–Sheet silicate

(b) I–ortho silicate, II–Sheet silicate and III–Cyclic silicate

(c) I–Cyclic silicate, II–Sheet silicate and III–Ortho silicate

(d) I–Sheet silicate, II–Ortho silicate and III–Cyclic silicate

Ans. (a)

Sol. ZrSiO4 is a ortho silicate because it contain SiO44– unit.

Be3Al2Si6O18 contains (SiO3)2– unit and is a cyclic silicate.

Al2(OH)2[(Si2O5)2] is a sheet silicate.

Correct option is (a)

36. A particle in one dimensional box of length 2a with potential energy

is perturbed by the potential V´ = cx eV, where c is a constant. The 1st order correction to the 1st excited state of the system is _________× c eV.

Ans. 0

Sol. Length of box is 2a, between limits –a to a

Wavefunction for 1st excited state for such a system is

1st order correction would be

37. The product obained in the reaction of Mn2(CO)10 with Br2 is

(a) Mn(CO)5Br

(b) Mn2(CO)8Br2

(c) Mn(CO)4Br2

(d) Mn2(CO)9Br

Ans. (a)

Sol. Mn2(CO)10 + Br2 2Mn(CO)5Br

Correct option is (a)

38. Character table of point group D8 is given below

Value of (a + b + c + d + e + f + g + h + i + j + k) is equal to ________

Ans. 9

Sol. Using 2nd and 3rd postulate of GOT, we find that

a = b = c = d = 1

e = f = g = 2

h = i = j = – 1

k = 2

a + b + c + d + e + f + g + h + i + j + k = 9

39. In the following reaction sequence, the products P and Q are

(a)

(b)

(c)

(d)

Ans. (b)

Sol.

Correct option is (b)

40. Consider the electrochemical cell

M(s)|MI2(s)|MI2(aq)|M(s)

where 'M' is a metal. At 298 K, the standard reduction potential are

and the temperature coefficient is

. At this temperature the standard enthalpy change for the overall cell reaction, is ________ kJ mol–1. (Round off to two decimal place)

(Faraday constant F = 96500 C mol–1)

Ans. –37.693

Sol. M(s) | MI2(s) | MI2(aq) | M(s)

Using

= – (2)(96500) [Eº – 298 (1.5 × 10–4)]

= –(2 × 96500) (0.24 – 298 × 1.5 × 10–4)

= –37.693 kJ mol–1

41. In the following reaction sequence, the products P and Q are

(a)

(b)

(c)

(d)

Ans. **

Sol.

42. The normal boiling point of a compound (X) is 350 K (heat of vaporization, = 30 kJ mol–1). The pressure required to boil 'X' at 300 K is ________ Torr. (Round off to two decimal places)

(Ignore the temperature variation of ; Gas constant R = 831 J mol–1 K–1 and 1 atm = 760 Torr)

Ans. 136.32

Sol. T1 = 350 K, P1 = 760 torr

T2 = 300 K, P2 = ?

Using Clayperon equation

P2 = 136.32 Torr

43. The rate of the following redox reaction is slowest when X is

(a) H2O

(b) NH3

(c) Cl

(d) N3

Ans. (b)

Sol. When X = NH3, then it is not a good leaving group so rate of reaction will be slowest

Correct option is (b)

44. In the following reactions, the major products P and Q are

(a)

(b)

(c)

(d)

Ans. **

Sol.

IF R = H

IF R = COEt

45. For a biomolecular gas phase reaction P + Q R, the pre-exponential factor is 1 × 1013 dm3 mol–1 s–1. The standard entropy of activation at 25ºC is ____________ J K–1 mol–1. (Round off to two decimal points)

(The standard concentraiton cº = 1 mol dm–3; Planck constant h = 6.62 × 10–34 J s; Boltzmann constant kB = 1.38 × 10–23 J K–1; Gas constant R = 8.31 J mol–1 K–1)

Ans. –12.67

Sol.

46. Match the metalloproteins with their respective functions.

(a) P - III; Q - II; R - I; S - IV

(b) P - III; Q - I; R - IV; S - II

(c) P - IV; Q - I; R - III; S - II

(d) P - IV; Q - II; R - I; S - III

Ans. (b)

Sol. (P) Ferritin (III) Metal storage

(Q) Rubredoxin (I) Electron transfer

(R) Cobalamin (IV) Methyl transfer

(S) Carbonic anhydrase (II) Acid-Base catalysis

Correct answer is (b)

47. If , where and are spin angular momentum operators and is spin up eigen function, then the value of 'a' is __________. (Round off to one decimal place)

Ans. 0.5

Sol.

a = 0.5

48. The major product formed in the following reaction is

(a)

(b)

(c)

(d)

Ans. **

Sol.

49. Among the following compounds, a normal spinel is

(a) MgFe2O4

(b) ZnFe2O4

(c) CoFe2O4

(d) CuFe2O4

Ans. (b)

Sol. ZnFe2O4 is normal spinel amongst all.

CFSE of Zn2+ in oh site is less than CFSE of Fe2+ ion.

MgFe2O4 is example of inverse spinel due to high lattice energy of Mg.

Correct option is (b)

50. The major product formed in the following reaction is

(a)

(b)

(c)

(d)

Ans. (d)

Sol.

Correct option is (d)

51. The number of possible optically active isomer(s) for the following complex is _______.

en = ethylenediamine

Ans. 4

Sol.

No POS is present therefore it is optically active and it's mirror image also exist.

No POS is present therefore it is optically active and it's mirror image also exist.

Total number of optical isomers are 4.

Correct answer is 4.

52. The correct molecular representation of W(Cp)2(CO)2 is

(Cp = cyclopentadienyl)

(a)

(b)

(c)

(d)

Ans. (c)

Sol. W(Cp)2(CO)2 It follows 18e rule.

x + y = 18 – 10 = 8

x + y = 8 x = 3, y = 5 or x = 5, y = 3

Hence is the correct option.

Correct option is (c)

53. Consider a two dimensional harmonic oscillator with angular frequency = 6.5 × 1014 rad s–1. The wavelength of x polarized light required for the excitation of a particle from its ground state to the next allowed excited state is _______× 10–6 m. (Round off to one dimensional place)

(Speed of light c = 3.0 × 108 m s–1)

Ans. 2.9

Sol. Wx = 6.5 × 1014 rad s–1 = 10.35 × 1013 sec–1

Wy = 3.25 × 1014 rad s–1 = 5.175 × 1013 sec–1

Energy of ground state in sec–1

Wavelength required for transition is equal to energy difference between two states,

in 'm'

Correct answer is (2.9)

54. Consider the following two parallel irreversible first order reactions at temperature T,

where k1 and k2 are the rate constants and their values are 5 × 10–2 and 15 × 10–2 min–1 respectively, at temperature T. If the initial concentration of the reactant 'P' is 4 mol L–1, then the concentration of product 'R' after 10 min of reaction is ________mol L–1. (Round off to two decimal places)

(Assume only P is present at the beginning of the reaction)

Ans. 2.59

Sol.

= 3 [1 – e–2]

= 2.59

55. The major product formed in the following reaction is

(a)

(b)

(c)

(d)

Ans. (d)

Sol.

Correct option is (d)