IGNOU BCHCT-135 December 2024 Previous Year Question Paper

Q1.(a) What is a tie line in a liquid-vapour phase-composition curve for an_ ideal solution ? 1

(b) Calculate total vapour pressure of the solution having one mole each of benzene and toluene at 298 K. The vapour pressure of pure benzene and pure toluene are

Q2.25x104 Pa and 3.70108 Pa, respectively.

Q3.(a) Define Critical Solution Temperature (CST) for partially miscible liquid pairs. How will the CST of Phenol-Water system change upon addition of

(i) KCl and

(ii) Sodium oleate ? Also give reason(s). 3

(b) State Nernst’s distribution law and give its limitations.

Q4.Zinc (m. p. 419°C) and Magnesium (m.p. 851°C) form a compound, MgZnz2 (m.p. 575°C). Two eutectic points are observed at 380°C; 80 mass % to zinc and 345°C; 40 mass % to zinc. Draw a schematic phase diagram for the system and label different regions in it.

Q5.(a) Consider the following equilibrium : 2 PCI;(s) = PCl3

(g) + Cly

(g) Calculate the number of components in a system containing a mixture of PCls(s), PCls

(g) and Cle

(g).

(b) (४) Draw schematic graphs for conductometric titration curves for HCl vs. NaOH and CH3COOH us. NaOH. 2

(ii) Can we titrate a mixture of HCl and CH3sCOOH vs. NaOH using a conductometer ? Comment.

Q6.(a) List any four applications of conductivity measurements. 2

(b) In’ moving boundary’ method for determination of transport number of Li*, a

Q7.05 M solution of LiCl was taken in a cell having cross-sectional area of 2.1 cm2. At the end of experiment the boundary was moved by 1.17 cm and 0.0415 g of silver was deposited on the cathode of silver coulometer. Calculate the transport number of Lit ion.

Q8.(a) Calculate Ey for the reaction occurring in the following voltaic cell : 3 Fe, | Fe” (aq,a =1) Ca”*(aq,a = 0) Cd Given: E® 5, =-0.41V Fe*"| Fe Ee yet oq = 70-40

(b) Calculate the equilibrium constant for the reaction occurring in the cell.

Q9.(a) Write half cell reaction and corresponding Nernst equation for quinhydrone electrode for pH measurement of a solution. 3

(b) State Faraday’s first and second laws of electrolysis. 2 Part-B (Marks : 25)

Q10.Complete the following reactions :

Q11.LiAlH, _LiAIH, OCH; . C Brot

(ii) RCH,COOH—p-45> N2Cl

(ii) OO —FRS0.TRO ५ GHO . HN Gv) (CHOW), HNO, _, CH,OH NO>

Q12._1.FeHCl ™) CO 2. NaOH

Q13.(a) Explain giving suitable structures why D-(+)-glucose and D-(+)-mannose give same Phenyl-Osazone derivative. What are such sugars called ? 4

(b) What is isoelectric point ?

Q14.(a) How will you distinguish between primary, secondary and tertiary aromatic amines using Liebermann nitroso reaction ? 3

(b) Which carboxylic acid derivative is most reactive towards nucleophilic acyl substitution and why ?

Q15.(a) Why is p-nitroaniline less basic than p-methylaniline ? 2

(b) Draw the Haworth’s projection formula for B -D-glucofuranose. 2

(c) What are anomers ?

Q16.Discuss the secondary structure of proteins with suitable diagrams.

Q17.(a) Write all the steps for the synthesis of alanine using Strecker synthesis. 3

(0) Explain the mechanism of _ Fischer esterification by taking a _ suitable example.

Q18.(a) Convert D-erythrose to D-arabinose by Kiliani-Fischer synthesis. Show all the steps. 3

(b) What is mutarotation ?

Q19.25 101 98 और 3.70x10? Pa @I 4 Fey | Fe®* (aq,a =1) Ca*(ag,a = 0) | Cd E° 4, =-0.40V —Cd? Ca —coon, (i O _LiAIH, Gi) RCH,COOH— P34 an Cy) seat, ie HNO.

(iv) (CHOH), a, CH,OH NO» © OO a Non