IGNOU BCHCT-133 June 2025 Previous Year Question Paper

Q1.(a) Which of the following P-V diagrams best represents an isothermal process for an ideal gaseous system ? 2 (ai) wae P

(b) The molar heat capacity of water at constant pressure is 75 JK-! mol. What would be the increase in temperature of 1 kg of water when 10 kJ of heat is supplied to it ?

Q2.(a) State the Zeroth Law of Thermodynamics. 2

(b) For complete combustion of ethanol : C,H;0H + 30५

(8) -> 200५

(8) + 39५00) the amount of heat produced as measured in bomb calorimeter is

Q3.0 kJ mol! at 27°C. Assuming ideality, what would be the molar enthalpy of combustion, AcH for the reaction ? (Given : R= 8.314 JK"! mol-1.)

Q4.(a) What are spontaneous reactions ? Give any one criterion of spontaneity of a reaction. 2

(b) Diborane undergoes combustion according to the reaction : B,Hg

(g) + 30,

(g) > B,O3(s) +3 H,O

(g) What would be the enthalpy change for the combustion of diborane ? 3 Given :

Q5.28

(8)+ 302

(g) > B,O3

(8) ; AH =—1273kJ/mol AH =—286kJ/mol

(iii) H,O@) > H,O

(g); AH = 44kJ/mol

(iv) 28७) + 3,

(8) > BoHg

(g); AH = 36kJ/mol

Q6.(a) Derive the relationship between Kp and Ke for the following equilibrium reaction : 2 2S09

(g) + Oo

(g) = 2S03

(g)

(b) Given the following equilibrium reaction, predict the direction of shift of equilibrium for each stress listed : 3 A,H =171kJ mol

(i) addition of CO

(ii) increase in pressure

(ii) addition of a catalyst.

Q7.(a) One mole of ice is converted into water at 273 K and 1 atm. The molar entropies of H,O(s) and H2O are

Q8.20 and 60.00 J mol! K-41, respectively. What would be the enthalpy change for the conversion? 2

(b) Explain enthalpy driven and entropy driven reactions. Melting of ice is an endothermic process. Is the process ‘entropy driven’ or ‘enthalpy driven’ ? Justify your answer.

Q9.(a) State Ostwald’s dilution law. Write the mathematical expression for the Ostwald’s dilution law. 2

(b) What is the pH of a solution which is prepared by mixing 100 cm? of 0.01 M HCl and 300 cm? of 0.02 M NaOH at 298K? 3 Given : log 2 = 0.30; log 3 = 0.48, log 8 = 0.90.

Q10.(a) Formic acid (HCOOH) is a weak acid. Write the ionisation equilibrium reaction for formic acid in water and also give the expression for the corresponding ionisation constant. 2

(b) What would be the pH of buffer solution containing 0.17 M acetic acid and

Q11.34 M sodium acetate ? Given : pKacacetic acid) = 4.74; log 2 = 0.30; log 3 = 0.48. 3 Part—B (Marks : 25) (Functional Group Organic Chemistry—I) Note : Attempt any five questions from Question Nos. 8 to 14.

Q12.(a) How is nitrobenzene obtained from benzene ? What is the role of conc. H2SOz in this reaction ? Explain. 3

(b) Which of the following compounds will be obtained on nitration of nitrobenzene ? Why ? 2 NO, | NO, NO, » OL NO, NO, eae C3

(iii) | NO,

Q13.(a) Write all the steps involved in the conversion of aniline to chlorobenzene. Write the specific name of each reaction. 2+1

(b) What type of elimination reaction (E1 or Ez) does CH3sCHe2Cl undergo on treatment with a strong base ? Write its reaction.

Q14.Complete the following reactions :

Q15.O +Br, Lewisacid - AICL

(i) CO +cH,coc) “Cs_,

(1) CH,CHO + cone.NaQH—4->

(iv) CH3COCH, + 1, + NaOH——> CHO NHNH2 NO? HS! ) Oo * cr a NO>

Q16.(a) Give the structure of the simplest trihydric alcohol. Write its IUPAC and common name. 2

(b) How is phenol obtained by cumene- phenol process ? Write stepwise the reagents used and_ products formed.

Q17.(a) State Huckel’s rule. Which of the following are aromatic and why ? 3

(iii) U3

(b) State Saytzeff’s rule. What will be product by elimination of H-Clfrom 2 CH,CH, —CH- CH, ?

Q18.Explain the following : 5

(a) 2, 4-dinitrophenol is a stronger acid than phenol.

(b) CHsCHO undergoes Aldol condensation but not HCHO.

Q19.(a) Explain why p-chlorotoluene gives a mixture of m-toluidine and p-toluidine on reaction with sodamide. What is the name of the intermediate in this reaction ? 3

(b) How will you convert CHsMgCl to the following : 2

(i) CHs3—CH3

(ii) CHsCOOH ay =P Dy.

(iv) L~ mol! @1 af 1 kg Wt Hl 10 kJ SOT की B,H,

(g) +302

(g) > B,O3(s) + 3H,O

(g)

Q20.2Bis)+ 302

(g) > B,O3(s) ; AH = -1273kJ/mol 7 1 Gi) Hy

(g)+ 2 0५

(8) -2 9200); AH =-286kJ/mol

(ii) H,O@) > H,O

(g); AH = 44kJ/mol

(iv) 2B(s)+3Hp

(g) > ByHg

(g); AH = 36kJ/mol 2803

(g) + O2

(g) =2803

(g) ws we wa के far we A,H=171kJ mol

Q21.00 J mol? K+ @1 ga wary & fa (@) 0.01 M HCl & 100 cm? a2 0.02 M NaOH log 8 = 0.90. pKa aay = 4.74; log 2 = 0.30, log 3 = 0.48. 3 NO, | NO, @ ion NO, NO, NO,

(iii) CI NO, @ CO + Br, Ee,

(ii) CO +CH,COCI AIC;

(iii) CH,CHO + cone. NaOH—4-»

(iv) CH,COCH, +1, + NaOH——> CHO NHNH3 NO?

(ii) U

(iii) U

(ख) Fearn a Fas aaeu! fFrafafad & H-Cl CH,CH, -¢ H-CH, (@) CH3MgBr @ ay Frafetad 4 Sa waite

Q22.CHs—CHs

(ii) CHsCOOH