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

Q2.State five postulates of Dalton’s atomic theory.

(5)

Q3.(a) Calculate the de Broglie wavelength associated with an object having mass

Q4.2 x 102 kg moving with a velocity 10 ms“.

(b) State the method involved in the application of Schrédinger equation for calculating the dynamic variables of a system.

Q5.(a) Explain why NO is paramagnetic and NO* is diamagnetic. 3

(b) Write Lewis structures of HCN and HNO.

Q6.(a) Define ionisation energy and write the units used to measure it. 2

(b) Arrange the following in the increasing order of ionisation energy : Na, K, Li Also, give reason for your answer.

Q7.(a) What is Hund’s rule ? Explain giving a suitable example. 2

(b) Write electronic configuration of Fe. (Atomic number of Fe is 26.) 1

(c) Write the hybridisation of carbon atoms in HeC = CH —- CH = CH.

Q8.(a) Write the possible values of all the quantum numbers for the electrons present in a 2s orbital. 4

(b) Using VSEPR theory, predict the shape of carbonate ion.

Q9.(a) Define lattice energy. 1

(b) Write two main contributing resonance structures of cyanate ion. 2

(c) Draw the molecular orbitals formed when a hydrogen molecule is formed from hydrogen atoms. Also name _ these molecular orbitals. 2 Part—II (Marks : 25) Note : Attempt any five questions.

Q10.(a) Give the mechanism of the reaction of methane with chlorine in presence of sunlight. 3

(b) How is cyclopropane converted to

(i) n- propane and

(ii) 1-bromopropane ?

Q11.(a) Which of the following carbocations is most stable and why ? 3 (CH,),C*, CH,CH,CH, CH,, CH,CH,C HCH,

(b) How will you convert ethyne to

(i) 1-butyne and

(ii) 1, 1-dibromoethane ?

Q12.(a) Write the structures of enantiomers and diastereo-isomers of tartaric acid. 4

(b) Draw the structure of the isomer of CHCl = CHC! which has dipole moment.

Q13.(a) Assign Z/E configuration to the following compounds and explain your answer : 3 Br CHO I CH, H CHO a \ 4 Gi) ve = Q D ‘CH,OH

(b) Write all the resonance structures of aniline.

Q14.(a) What is the structure to the alkene which gives acetone on ozonolysis ? Write all reactions involved. 2

(b) Arrange the following in the increasing order of acid strength : 3 CH,COOH, C,H;COOH, HCOOH Also give reason in support of your answer.

Q15.(a) State whether the following are aromatic or not : 2 Give reason for your answer.

(b) State and explain Markownikoff’s rule using a suitable example.

Q16.(a) Draw the Newman projections of the following conformations of n-butane : @) fully eclipsed conformation

(ii) fully staggered conformation Which one of the two is more stable and why ? 3

(b) Give one example each of the following reactions : 2 @ Birch reduction Gi) Retro Diels-Alder reaction Na, K, Li (CH,),C*, CH,CH,CH, CH,, CH,CH, CHCH, Br ae

Q17.or i ‘cH, H CHO Gi) Ye =c* D \cH,OH CH,COOH, C,H;COOH, HCOOH

Q18.1. 0.