IGNOU BCHCT-131 December 2024 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—I (Marks : 25) Note : Attempt any five questions.

Q2.(a) Calculate the wave number, vo and frequency of a light of wavelength 480 nm.

(b) Find the values of principal, azimuthal and magnetic quantum numbers of an electron in a 3d orbital.

Q3.(a) Write the electronic configuration of Gd (atomic number 64) and Pd (atomic number 46). 2

(b) Explain the terms eigen function and eigen values. 2

(c) What is Laplacian operator ?

Q4.(a) Write the postulates of Bohr’s model. 4

(b) What is energy value of an electron if n=4?

Q5.(a) Electron affinity of carbon is — 122 kJ mol"! while that of nitrogen is + 9 kJ mol-!. Explain. 2

(b) Explain two salient features of blackbody radiation. 2

(c) Give any two characteristics of a well behaved wave function.

Q6.(a) State Aufbau’s principle for filling of electrons in orbitals. 2

(b) Write the molecular orbital configuration of Og molecule. Calculate its bond order and also explain its magnetic behaviour.

Q7.(a) Using VSEPR theory, predict the shape of SF molecule. 3

(b) The dipole moment of HBr is 2.60 x 103° Cm and the internulcar distance is 141 pm. Calculate the percentage of ionic character in HBr.

Q8.(a) Write resonance structures of HNs. 3

(b) Draw a suitable diagram for the bonding and anti-bonding molecular orbitals formed from the overlap of s and px atomic orbitals. 2 Part—II (Marks : 25) Note : Attempt any five questions.

Q9.(a) Give the product(s) formed in the given reaction : CH, - CH, - Cl ae Name the reaction involved. 2

(b) Complete the following reactions : 2 OBE ng

(ii) Hy02,0H-

(ii) CH, -CH+HCN—— ?

(c) Draw the structure and _ give the hybridization of methyl carbocation (CH3).

Q10.(a) What are meso compounds ? Explain using a suitable example. 2

(b) Draw all possible stereoisomers of the given compound using Fischer projections : H;C, ~¢H- ¢H-COOH CH; OH

(c) Amongst the given compounds, identify the one that will exhibit geometrical isomerism : CH; —-CH, —- C=CHy, bu, CH; —-CH, -CH = CH-CH3;,

Q11.(a) Assign priority order to the groups attached and assign R or S configuration to the given compound : 2 CHO H,C = HC +— CH,CH3, CHs

(b) Draw the Sawhorse and Newman projections of the given compound : 2 CHO H OH H OH CH,OH

(c) Draw the resonance structures of the compound : 1 CH, —-C-N Hy,

Q12.(a) From the following compounds, identify the compound with higher acid strength. Give reason in brief : 2 CH —CH, —-COOH, CH; -— ¢H- COOH Cl Cl

(b) Suggest a method for the synthesis of propyne using 1, 2-dibromopropene. 2

(c) In the given reaction, identify the conjugate acid and conjugate base : 1 CH,COOH + H,O = CH;COO + H,0*

Q13.(a) Explain why acid catalysed dehydration of pentan-2-ol gives pent-2-ene as the major product. 2

(0) Deduce the structure of starting alkene/alkyne from the given products of ozonolysis : 1 CHsCHO and HCHO CH;

(c) Give the IUPAC name of Ch Jo

(d) Using Huckel’s rule, predict which of the given compounds’ will exhibit aromaticity :

Q14.(a) Arrange the following in order of increasing boiling points, giving reason(s) in brief : 3 CH; -CH-CH,, CH; -CH-CH,-CHs, CH3 CH; CH; - ९ —CHs CH,

(b) Give the steps involved and product(s) formed in the monochlorination of ethane by free radical halogenation.

Q15.(a) Complete the following reactions : 3 CH; —- CH- He Gi) CH, =CH,

(i) perbenzoic acid 9 ii) C alcoholic

(iii) CH, 7९ — Br —NaoH हट

(b) Draw the Fischer projection of the given compound : 1 COOH HO teh 4 CH2OH

(c) Draw the proton tautomer of the following :

Q16.(%) HA st getagt aye — 122 kJ molt wate aegis ot geegid ae + 9 kJ

(ii) Hp02,0H-

(i) CH, -CH+HCN——>? CH; OH CHy CH; -CH, -CH =CH-CHs, CHy CHO H,C =HC +— CH,CH, CH, CHO H OH H OH CH,OH CHa —CH, -COOH, CH, - ¢H-COOH Cl cl CH,COOH + H,O0 = CH,COO- + H,0* CH3CHO a HCHO CH ~CH—CHs, CH ~ CH - CH ~ CH CH; CH; CH; - CH - CH,

(i) CH, =CH, TEE ee

(a) a

(ii) CH, -C - Br —“Sieistl_,» | NaOH CH; HO my CH20H