RGU Question Paper Chemistry Semester VI 2020: Physical Chemistry

 

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B.Sc (VI Semester) Examination

CHEMISTRY

Paper : CHEM–361

( Physical Chemistry )

Full Marks : 80

Pass Marks : 35%

Time : Three Hours

Note : 1. Answer all questions.
2. The figures in the margin indicate full marks for the questions.
3. The symbols used are of usual meaning.

1. Answer any five questions : 2×5=10

(a) Discuss coagulation of colloids.

(b) $T{h}_{92}^{234}$ disintegrates to give $P{b}_{82}^{206}$ as the final product. How many alpha and beta particles are emitted in this process?

(c) What is Ziegler-Natta catalysis?

(d) Discuss Compton effect.

(e) What are spherical and symmetric top molecules? Give an example.

(f) Write the expression of Hamiltonian operator for a particle moving in a three-dimensional box.

(g) How does addition polymerization differ from condensation polymer?

2. Answer any four questions : 5×4=20

(a) What are emulsions? Describe its types and preparation of emulsion. 1+4=5

(b) The half-life period of radioactive element is 19·5 days. In how much
time will a gram of pure element (i) loose one centigram and (ii) be
reduced to centigram?

(c) A polymer consists of 40% by weight of macromolecule of molecular weight 10000 and 60% by weight of macromolecule of molecular weight 75000. Calculate the number average molecular weight of macromolecule.

(d) A particle of mass m is confined in a one-dimensional box of length a. Calculate the probability of finding the particle in the region, where $0\le x\le a/2$.

(e) The rotational spectrum of HCl molecule shows that the rotational lines are equally separated by 20·70 $c{m}^{-1}$. Calculate the internuclear bond length.

(f) A solution contains 1 : 2 ratio of the number of particles of two substances with molar masses 10 kg $mo{l}^{-1}$ and 20 kg $mo{l}^{-\mathrm{1 }}$respectively. Calculate the number average and weight-average molar masses.

3. Answer any five questions : 10×5=50

(a) Derive Langmuir’s adsorption isotherm and discuss its limitations.

(b) (i) What do you mean by radioactive equilibrium?
(ii) A wooden artifact sample gave activity of 32 $\beta$-particles per second while the freshly cut wood gave activity of 64 $\beta$-particle per second. Calculate the age of wooden artifact ($t_{1/2}$ of c = 5760 yrs).

(c) Define number-average and weight average molecular weights of macromolecules. Discuss viscosity method of determining molecular weight of a macromolecule. 4+6=10

(d) Derive Schrödinger wave equation using de Broglie concept.

(e) Derive the expression for rigid rotator and discuss the effect of isotopic substitution on rotational spectra. 7+3=10

(f) Write notes on : 5×2=10
(i) Condensation polymerization
(ii) Stability of colloids

(g) The un-normalized wave function of a particle moving in a one dimensional
box of width a is ${\psi }_n=N\sin \left(\frac{n\pi }{a}\right)x$. Normalize the wave
function.

RGU Question Paper-2020
B.Sc. VI Semester Chemistry
CHEM-361: Physical Chemistry