Physical Chemistry-Chemistry-BSC-Nagpur-Summer-2017
Bachelor of Science (B.Sc.) Semester—1 Examination
CHEMISTRY (Physical Chemistry)
Optional Paper—1
Time : 3 Hours
Maximum Marks : 50
N.B. :— (1) All questions are compulsory and carry equal marks.
(2) Draw well labelled diagram wherever necessary.
1. (A) State and deduce the following from kinetic gas equation :
(i) Avogadro’s law and
(ii) Graham’s law of diffusion. [5M]
(B) Define :
(i) Critical volume
(ii) Critical temperature and
(iii) Critical Pressure.
The critical temperature and critical pressure of chlorine are 419 K and 93.1 atmosphere respectively.
Calculate the van der-Waal’s constants for chlorine gas. [5M]
OR
(C) Discuss Maxwell-Boltzmann’s distribution of molecular velocities. [2½M]
(D) Calculate the temperature at which RMS velocity of oxygen molecule will be equal to Hydrogen
molecule at 20 K. [2½M]
(E) Give the explanation of deviation of real gases by means of van der Waal’s equation of state. [2½M]
(F) Explain compressibility factor and Boyle temperature. [2½M]
2. (A) Derive Bragg’s equation for diffraction of X-rays. The first order diffraction from a certain crystal
is observed at an angle of 20.6° with X-rays of wavelength 22.91 nm. Calculate the interplanar
spacing. [5M]
(B) State and explain :
(i) Law of constancy of interfacial angles and
(ii) Law of rationality of indices. [5M]
OR
(C) What are Miller indices ? The Weiss indices of a certain plane are
3
1
,
2
1
and ¥. Find Miller
indices. [2½M]
(D) Draw (100), (110) and (111) planes of simple cubic crystal. [2½M]
(E) Discuss Laue’s method for determination of crystal structure. [2½M]
(F) Why Bragg’s method show that KCl is simple cubic though it is face centred cubic like
NaCl ? [2½M]
3. (A) What are intermolecular forces ? Discuss the following intermolecular forces in liquids :
(i) Dipole—induced dipole interactions and
(ii) London forces. [5M]
(B) How surface tension of a liquid is determined by capillary rise method ? At what height will a
liquid rise in a capillary tube having 0.1 mm diameter ?
(Density of liquid = 1.3 × 103 kgm–3
Surface tension of liquid = 6.5 × 10–3 Nm–1
Acceleration due to gravity = 9.8 ms–1). [5M]
OR
(C) What are liquid crystals ? Discuss cholesteric liquid crystals. [2½M]
(D) How relative viscosity of a liquid is determined by Ostwald’s viscometer ? [2½M]
(E) The molar refraction of acetic acid is 13.3 × 10 –6 m3 mol–1 and its density is 1.046 × 10 3 kgm–3.
Calculate refractive index of acetic acid. [2½M]
(F) What is parachor ? Discuss application of parachor in structure determination. [2½M]
4. (A) Give the assumptions and derive an expression for Langmuir adsorption isotherm. [5M]
(B) Write BET equation. How is it used in the determination of surface area of the absorbent ? [5M]
OR
(C) What are the important applications of adsorption ? [2½M]
(D) Explain with examples homogeneous and heterogeneous catalysis. [2½M]
(E) Explain auto catalysis with examples. [2½M]
(F) Write a note on enzyme catalysis. [2½M]
5. Attempt any ten questions of the following :
(i) State any two postulates of Kinetic theory of gases.
(ii) Define mean free path.
(iii) Write van der Waal’s equation of state for n moles of real gas.
(iv) Define space lattice.
(v) Identify the crystal structure with the dimensions of unit cell :
a = b = c and a = b = g ¹ 90°
(vi) Draw unit cell of CsCl.
(vii) Why the liquid drop is spherical ?
(viii) What is intrinsic viscosity ?
(ix) Define refractive index.
(x) What are inhibitors ?
(xi) Define the term chemical adsorption.
(xii) Write Michaelis-Menten equation. [10M]