IGNOU BCHCT-131 December 2022 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 from question nos. 1 to 7.

Q2.(a) Calculate the wave number, V and frequency of a_ light of wavelength, A’ = 300nm. 2

(b) What is a well-behaved wave function ? Explain using suitable diagram.

Q3.(a) Find the values of principal, azimuthal and magnetic quantum numbers of an electron in a 4d orbital. 3

(b) Write the electronic configuration of the elements La (atomic no. 57) and Sr (atomic no. 38).

Q4.(a) Justify the fact that formation of Li* ion is easier than that of Ne* ion. 2

(b) Give any three limitations of Bohr’s theory.

Q5.(a) The ionic radii of Lit and Be?* are 60 p.m. and 31 p.m. respectively though they are isoelectronic. Give reason. 1

(b) What is photoelectric effect ? How did Einstein explain it ?

Q6.(a) State Hund’s rule for filling of electrons in orbitals. Give its reason. 2

(b) Write the molecular orbital configuration of Oz molecule and calculate its bond order.

Q7.(a) The charge on H atom in HCl is

Q8.8 x 102° C and the bond length is

Q9.5 p.m. Calculate the dipole moment of HCl in Cm and also in Debye units. 2

(b) Using VSEPR theory, predict the shape of IF; molecule.

Q10.(a) Write resonance structures of nitrate ion. 3

(b) Draw suitable diagrams for the bonding and anti-bonding molecular orbitals formed from overlap of two py orbitals. 2 Part—II (Marks : 25) Note :Attempt any five questions from question nos. 8 to 14.

Q11.(a) What are Brénsted acids and bases ? Give one example of each. 3

(b) Which of the following compounds can exhibit geometrical isomerism ?

Q12.CHCl= CHCl Gi) CHz = CHCl

(c) Assign Z/E configuration to the following compound : 1 CH. OH H5C5 ‘OCH,

Q13.(a) Give the name of type of the each reaction shown below : 3 po CH,X — CH,X — CH, CH, = CHCH, —“—, CH =C-CH, Gii) _, CH, = CH - CH,X

(b) Give one example each of position isomers and chain isomers.

Q14.(a) Which of the following compounds can have diastereoisomers ? Write the Fischer projections of the diastereoisomers : 3

(i) CHsCHOHCOOH

(ii) COOH — CHOH — CHOH - COOH

(b) Why is the boat conformation of cyclohexane less stable than the chair conformation ?

Q15.(a) Define the following terms : 3 G) Racemic mixture Gi) Racemisation Gii) Resolution

(b) Which is aromatic— _ cyclopentadienyl carbanion or cyclopentadienyl carbocation ? Give reason.

Q16.(a) Define the terms

(i) nucleophile and

(ii) electrophile giving one example of each. 3

(b) Write the structures of the tautomers for the following : 2

(ii) CH, - CH, - C- CCH),

Q17.(a) Write the product of addition reaction of HBr to propene. What product will be formed when this reaction is done in the presence of peroxide ? 2

(b) Write the product of ozonolysis of CH; - C = C-CH3. 1

(c) How is cyclohexene prepared using Diels- Alder reaction ?

Q18.(a) Arrange the following carbocations in an decreasing order of their stability : 3 RCH,, RCH — CH = CH), R,CH Explain your answer.

(b) Write one reaction each for the following : 2 @)_ Addition polymerisation

(ii) Condensation polymerisation P.T.0.

Q19.5 pm. @! HCl # fey art cm ak @) CHCl= CHCl Gi) CH» = CHCl CH, OH N 4 Hoch Noch pe CH,X — CH)X — CH CH, = CHCH, —“—, CH =C-CH, Gii) _, CH, = CH - CH,X

(i) CHsCHOHCOOH

(ii) COOH — CHOH — CHOH - COOH

(ii) CH, — CH, — C- C(CHy), (@) CH,-C=C-CH, ® ainifefaa 4 RCH, RCH- CH = CH, R,CH