CHEMISTRY
Paper I
IMaximum Marks: 200 1
ITime Allowed Three Hours I
INSTRUCTIONS
Candidates should attempt questions 1 and 5 which are compulsory, and any THREE of the remaining questions, selecting at least ONE question from each Section. The number of marks carried by each question is indicated at the end of the question. Assume suitable cUita, if considered necessary, and indicate the same clearly. Answers must be written in ENGLISH. Unless otherwise indicated, symbols and notations have their usual meanings. (Planck's constant h =6·62 x 10-34 Js Boltzmann constant k 1-38 x 10-23 J Ir'l Electron rest mass m 9·1 x

SECTION A
1. Answer any four of the following
Show that free energy change -deltaGpT is the total amount of non-mechanical work. 10
Give a short account of "liquid crystals". 10


Given the following 0


EAg, AgBr =-0·073
. 1
K for the reaction Ag AgBr IS
2
6·46 x 1016 at 25° calculate E 0 Br2·Br-
Write the suitable chemical cell.
10

Explain the Graham's law of effusion. 10


Calculate the freezing temperature of water when the pressure is increased by two atm.


(6.H =79·9 cal p. 0·92 g cc-l.
lee PHg =13·6 g ce-.1.) 10
2. Explain the Maxwell's distribution of molecular
velocities and show that 2
mc
3/2 /de 41tn m c2e 2kT
c (
21tkT
J
where the number of molecules (of mass per ee, dnc de is the number of molecules per unit range of velocity, is the velocity and the rest of the symbols have their usual 20

2 lContd.]
"

Define a unimolecular reaction. Explain unimolecular reaction with the help of collision theory. Guess the order of the following reaction A B 2C D. 20
3. Discuss the principle" in detail. Show that for a macroscopic body this principle is of no importance. What was Einstein's opinion about this principle Discuss. 40
4. Show that. H2 Br2 order of reaction and inhibits the reaction. 2 HBr does not have an the formation of HBr 30
A first order decomposition reaction is characterised by a rate constant 4 x 10-2 min-t, Find out the time required to complete one-third of the reaction. 10

B-JGT-J-DIA 3 [Contd.l
SECTIONB

5. Answer any four of the following
Draw electronic atomic and molecular orbitals of 10
Draw the structure of dichromate ion solid
HF. 10

Explain the 'partition function'. Deduce the 'internal energy' and 'entropy' In terms of partition function. 10


Explain how the filling of 4£ energy level affects the rest of the periodic table. 10


What is 'relaxation Explain the 'relaxation method'in the study of rate of reaction. 10


6. Draw the shapes of various orbitals and explain as to why they are split in two groups e
g and t2g in an octahedral ligand field. 20
How do cryoscopiC and molar conductivity measurements help in establishing the structure of complexes? Explain with examples. 20
7. Discuss the laws of photochemistry, What IS meant by "One Einstein"
.On irradiation with light of 300 nm, propionaldehyde yielded CO. If the rate of formation of CO is 2·04 x 10-9 moles s-l and intensity of light is 10,000 ergs calculate the quantum yield of CO. 30
B-JGT-J-DIA
4 IContd.]
of energy of a 200 W lamp emits
visible light (A. =600 nm). How many quanta of
light is emitted per second 10
8. What is Born -Haber cycle? Using a modified
form of this cycle explain why Li is as strong a
reducing agent as Cs. 20
Discuss limitations and practical uses of liquid
ammonia as non-aqueous solvent. What happens
when 15NH4?1 is dissolved in unlabelled liquid
NH3 and the solvent .evaporated 20

B-JGT-J-DIA 5