IGNOU BCHCT-133 December 2025 Previous Year Question Paper

Q1.(a) What are intensive variables ? Identify intensive variables from the following properties : 2 @ Volume

(ii) Refractive index

(ii) Temperature

(b) Derive a_ relationship between the temperature and volume for an adiabatic process.

Q2.(a) Show that the heat absorbed by a system at constant volume is equal to increase in internal energy of the system. 2

(b) The reaction of cyanamide, NH2CN(s) with dioxygen was carried out in a bomb calorimeter, and AU was found to be — 742.7 kJ mol at 298 K. Calculate the enthalpy change for the reaction at 298 K: 3 NHCN@) + $09

(e) + No

(e) + 00:68) + H,0d)

Q3.(a) What are spontaneous reactions ? Give criteria for spontaneity of a reaction in terms of

(i) entropy, and

(ii) Gibbs energy. 2

(b) The enthalpy change for the following reaction is determined to be 131.28 kJ mol! at 298 K: C(eraphite) + Hg0

(g) > CO

(g) + Ho

(g) Calculate the enthalpy change for the reaction at 100°C. The C,° (JK-1 mol-}) values are given as : Cigraphite) = 8.53, : H2O

(g) = 33.58; CO

(g) = 29.12; H2

(g) = 28.82. Assume the heat capacity values to be temperature independent in the range.

Q4.(a) Write an equilibrium constant expression for each of the following chemical reactions : 2

(i) 4NOa

(g) + O2

(g) + 2H20

(g) = 4HNO3

(g)

(01) CHa

(g) + H20

(g) = CO

(g) + 3H2

(g)

(b) Calculate the equilibrium constant Kp and Ke for the reaction : O

(g) + 3 02) = COg

(g) Given that the partial pressure of various gases at equilibrium in a vessel at 3000 K are: 3 Pco = 0.4 atm., Pog, = 0.6 atm., Pog = 0.2 atm.

Q5.(a) Define chemical potential and give its significance. 2

(b) At a pressure of 1 bar, water undergoes fusion at 273.1 K. Write the equation for the process. Calculate the entropy of fusion of water if the molar enthalpy of fusion of water is found to be 6.02 kJ mol}.

Q6.(a) In the following reactions, label each species as an acid or a base. Also, identify the conjugate and acid-base pairs in these reactions : 2 (@) HS0j(aq)+ NH3(aq) = SO? (aq) + NHj(aq)

(ii) HPO} (aq) + NH} (aq) = HyPOj (aq) + NH3(aq)

(b) Calculate the degree of hydrolysis of

Q7.1 M aqueous solution of sodium acetate at 298 K. Given: 3 Ka(CH3COOH) = 1.8 x 107°.

Q8.(a) What is common ion effect ? Explain with the help of a suitable example. 2

(b) For PbCl2, ksp = 3.2 x 10-5. Determine the maximum amount of PbClz (in g) that will dissolve in 250 cm? of water at 25°C. 3 Given : Molar mass of PbCl2 = 278 g/mol Part—B (Marks : 25) (Functional Group Organic Chemistry—I) Note : Attempt any five questions from Question Nos. 8 to 14.

Q9.(a) Give TUPAC and common name of CgH;CH,Cl. 1

(b) State Huckel’s rule. Which of the following is aromatic ? 2

(c) What are electrophiles ? Give the structures of two electrophiles.

Q10.(a) Explain why t-butyl alcohol undergoes elimination reaction by Ei and n-butyl alcohol by E2 mechanism. 4

(b) Give two examples of o-, p-directing groups in electrophilic aromatic substitution reaction.

Q11.Complete any five of the following reactions :

Q12.CgH; Ne Cl io”

(ii) ae qe + Hooe—{)— COOH OH OH Polymerisation ii) RCOC] 72९4

(ii) RCOC1 —has0, ? a i) NH)NH2.HCl CgHs-COCH, —@NH2NH2-HCl_ Gv) CgHs-COCHS

(i) Base air

(v) Toor CofIIT] salt CH, Wi) a

Q13.How is benzene converted to acetophenone ?

Q14.Give the specific name of the reaction, its mechanism and one catalyst that is used in this reaction.

Q15.Complete any five of the following reactions : 5 CH(CH3)2 @ a air 2 (oxidation)

(ii) RCHO + (CH2COOEt)2 —> ?

(ii) RO-Nat + R'Cl—> ?

(v) 2CH,CHO —SLN20H_, »

(vi) OQ +CHClz —28,

Q16.Explain any five of the following : 5

(0) Why is benzene not used in under- graduate labs ?

(i) Role of conc. sulphuric acid in the nitration of benzene.

(iii) Hybridisation of carbon attached to —Cl in CH2 = CH-Cl.

(iv) Role of crown ethers in chemistry.

(v) A common laboratory test for aldehydes and ketones.

(vi) Why are phenols acidic in nature ?

Q17.Explain in short any two of the following: 5 @ Why do phenolphthalein show different colours in acidic and alkaline medium ?

(i) Why is —Cl in C6HsCl difficult to be substituted by a nucleophile as compared to that in (CH3)3CCl ?

(ii) Why CH3sCHO~ undergoes base catalysed Aldol condensation but not HCHO?

(ii) 7 C(graphite) + HyO

(g) > CO

(g) + 62

(8) Came) = 8.53; H20

(g) = 33.58; CO

(g) = 29.12; H2

(g) = 28.82.

Q18.4NO2

(g) + O2

(g) + 2H20

(g) = 4HNO3

(g) Gi) CHa4

(g) + H20

(g) = CO

(g) + 3H2

(g) Pco = 0.4 atm., Pog, = 0.6 atm., Po, = 0.2 atm.

(i) HSOj7(aq) + NH3(aq) = SO7" (aq) + NHj(aq)

(0) HPO} (aq)+ NHj (aq) = H2PO; (aq) + NH(aq) Ka(CH3COOH) = 1.8 x 10

(ख) 70019 % fag ksp = 3.2 x 10- 1 250 cm? = 278 gmol!

Q19.(*) CgH;CH,Cl # IUPAC wa aa नाम

(i) CgHs No Cl Oe Gi) CHa fH + wooe {= COOH Seer OH OH ii) RCOC] —H2/PA qui) RCOCI ps0, ww) C coc NH,NH).HCl

(iv) CgH;—COCH3 aa CH CH3

(v) QO Heeger CH,CH3 Wi) ed CH(CH3)2

(ii) RCHO + (CH2COOEt)2 —> ?

(iii) RO-Nat + R'C1—>?

(iv) RCOOH + R'—0H —E~, 2

(v) 2CH,CHO —SLNa0H_, »

(vi) O FCHCl, 20207 Gi) (CH3)3CCl #t geal 4 CeHsCl 4 - Cl