IGNOU BCHCT-133 June 2023 Previous Year Question Paper

Q1.Write your Enrolment number, course code and part title clearly on each of the two answer books.

(iii) Marks are indicated against each question. Part—A (Marks : 25) (Chemical Energetics and Equilibria) Note: Attempt any five questions from Question Nos. 1 to 7.

Q2.(a) What are intensive variables ? Which of the following are intensive variables ? 2 @ Energy Gi) Pressure

(ii) Temperature

(iv) Refractive Index

(b) The specific heat capacity of water is 4.18 J °C-1 g1. How much heat is required to increase the temperature of 10.0 g of water from 4°C to 14°C ?

Q3.(a) State Hess’ law of constant heat summation. Give its significance. 2

(b) The enthalpies of formation of CO

(g), COx2

(g), N2O

(g) and N2O.

(g) are -110, —393, 81 and 9.7 kJ mol-! respectively. Calculate the enthalpy change for the following reaction : 3 N20,4

(g) + 3CO

(g) > N,O

(g) + 3CO2

(g)

Q4.(a) What are spontaneous reactions ? State the criterion of spontaneity of a reaction. 2

(b) 1 mole of Argon gas behaving ideally is taken in a cylinder fitted with massless and frictionless piston and occupies a volume of 10 dm?. If the gas is reversibly expanded to five times its initial volume at 298 K, calculate the entropy change for the process.

Q5.(a) Write the equilibrium constant expression (Kp) for the following reversible reactions: 2

(i) NH,HS(s) = NH3

(g) + H2S

(g)

Q6.N2

(g) + Oo

(g) = 2NO)

(b) What are weak electrolytes ? List different factors that affect the ionisation of weak electrolytes.

Q7.(a) When will AG° be equal to zero for an equilibrium reaction ? 2

(b) The equilibrium constant for the reaction No

(g) + 3H>

(g) = 2NH3

(g) is 0.19 at 532°C.

(i) What is the value of K, if the equation is written as : 1 3 = 9 3 Noe) + 5 Fle) = NH

(g)?

(ii) What is the value of K, for the decomposition of ammonia gas ? 2NH3

(g) = 2N2

(g) + 3H2

(g)

Q8.(a) Define buffer solution. Give one example each of acidic and basic buffer. 2

(b) Calculate the degree of ionisation and concentration of H,O* ions in 0.01 M solution of formic acid at 298 K. 3 [Given : K, (HCOOH) = 2.1 x 10~ at

Q9.(a) Calculate the pH of 0.2 M aqueous solution of sodium butyrate. 2 [Given : K, for butyric acid is 2.0 x 10-5]

(b) What is common ion effect ? Explain with the help of a suitable example. 3 Part—B (Marks : 25) (Functional Group Organic Chemistry—I) Note: Attempt any five questions from Question Nos. 8 to 14.

Q10.(a) Complete any three of the following reactions : 3 @) CH,CH(BnCH; + CH,CH,ONa* C)H,OH Heat

(ii) CH3CH = CH, + Bry CH)Cl Room Temperature iii) ८ x ck H,0 Gii) CgH, N = NC) ——2—>

(iv) CHyCH,CH,CH,Br —“8\ >

(b) Benzene undergoes substitution reaction even through it contains three double bonds. Give reason.

Q11.(a) With appropriate example, how will you show that alcohols and phenols are acidic in nature. Which of two is a stronger acid ?

(b) How will you convert the following ? 2

(2)- CH,Br >

(2)- CH,CH,CH,OH

Q12.(a) Complete and give name of the following (any two) :

Q13.CgHscHO—"—, oes

(i) Na*H-/DMF

(b) Discuss Saytzeff’s rule with the help of an appropriate example.

Q14.Give the reaction involved in the following name reactions (any five) : 5 @) Wurtz’s reaction

(i) Sandmeyer reaction

(iii) Friedel-Crafts’ alkylation

(iv) Perkin reaction

(v) Rosenmund reduction

(vi) Houben-Hoesch reaction

(vii) Kolbe reaction

Q15.(a) Which of the following is more reactive towards Sy! reaction and why ? 3 Methy] chloride or tert-Buty] Chloride

(b) How will you convert phenol to @) p-bromophenol and

(ii) 2, 4, 6- tribromophenol ?

Q16.(a) How will you prepare

(i) an aldehyde from an acid chloride and

(ii) an aldehyde from an alcohol ? 2

(b) Discuss Pinacol-Pinacolone rearrangement with mechanism.

Q17.Write short notes on any two of the following : 5

(i) Sulphonation of aromatic hydrocarbon

(ii) Meta-directing deactivators

(iii) Crown ethers

(iv) Uses of alkyl halides

(ख) COG), COx

(g), N2O

(g) TA N2O.

(g) की

Q18.1. 0. N2O04

(g) + 3CO

(g) + N,0

(g) + 3CO2

(g)

(i) NH,HS(s) = NH;

(g) + H)S

(g) Gi) No

(g) + O2

(g) = 2NO

(g) N,

(g) + 3H2

(g) = 2NH;

(g) 5 Na

(e) +3 Hy

(g) = NH5

(g) 2NH3

(g) = 2No

(g) + 3H2

(g)

Q19.1. 0.

Q20.1 x 10) Ky = 2.0 x 105) CH;CH(Br)CH; + CH;CH,ONa* CjHsOH Heat

(ii) CH,CH = CH, + Bry CH,Cly iii) C x cl H,0 Gii) CgH, N = NCI) ——*—>

(iv) CHyCH,CH,CH,Br —“8\ >

Q21.1. 0.

(2)- CH,Br >

(0)- CH,CH,CH,OH

Q22.~CgHsCHO—K_, Gi) (Sp rcs

(iii) (CH3)4C - OH —QN2H_/DME _, aoe BCHCT-133 11,6

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