BSc Chemistry SEM V ATKT CHEMISTRY SEMV PHYSICAL CHEMISTRY Question Paper - Mumbai University | munotes

Questions asked in this paper

1. Q1 All questions are compulsory
2. Q2 Figures to the right indicate full marks
3. Q3 Use of log tables /non-programmable calculator is allowed Attempt any four of the following:
   • A. Derive an expression for frequency separation of lines in the rotational spectrum of a diatomic 5
   • B. i. The vibrational frequency of a molecule 3x Calculate the zero point energy. 3
   • ii. Draw a suitable diagram to explain the isotopic effect on energy level of rotational spectrum 2
   • C. Derive the general expression for frequency of R-branch lines. Diagrammatically show the 5 transition for Ro, Ri, R2 and R3 lines
   • D.i. A substance was exposed to radiation of wavelength 4.5 x m. The first Stokes line 3 appeared at 5.4 x m. Calculate the Raman Shift
   • ii. Calculate degree of vibrational freedom for and molecules. 2
   • E. What is meant by Raman Scattering? What are Stokes and Anti Stoke’s lines? How do they differ 5 from Rayleigh line?
   • F. Show that for an anharmonic oscillator the wave number of the fundamental and first overtone 5 bands are in the ratio of 1:2
4. Q2 Attempt any four of the following:
   • A. Derive thermodynamically the relation ATp= Kpx m. 5
   • B. i. State and explain Raoult’s law of lowering of vapour pressure. 3
   • ii. Explain “Reverse osmosis’. 2
   • C. State the important assumptions of collision theory of reaction rates. 5
   • D. Calculate the boiling point of a solution containing 1.02 g of anthracene (M = 176) in 70 g 5 chloroform. The boiling point of pure chloroform is 334.2 K. and its ebullioscopic constant is 3.85
   • E. Explain the ‘flash photolysis’ method to study fast reactions. 5 Describe Rast method to determine the depression in freezing point. 5
5. Q3 Attempt any four of the following:
   • A. Explain the construction and working of Scintillation counter. 5
   • B. Explain the important components of a nuclear power reactor. 5
   • C. The value for the reaction 27 Al+ > 5 is 6.7033MeV. Calculate the isotopic mass of 7H
   • D. 1. Distinguish between Natural radioactivity and Artificial radioactivity. 3 Define the following terms: i) Curie ii) Mass number Isotope 2
   • E. Explain the thermonuclear reactions occurring on earth. 5
   • F. The activity of a radioactive element falls to half its original value in 4.0 hours. Calculate the 5 decay constant and average life of the radioelement. Also calculate the time in which activity reduces to one tenth of its original value
6. Q4 Attempt any four of the following:
   • A. 1. State the postulates of Langmuir’s adsorption isotherm. 3
   • ii. Explain the use of surfactants in the food industry. 2
   • B. Explain the origin of electric charge on a colloid (any two methods) 5
   • C. i. State the BET equation and test the validity for it. 5 Distinguish between physical and chemical adsorption (any two points). 3 Define:- 1) Colloidal electrolytes ii) Micelle — Critical Micelle concentration 2
   • E. Explain the Donnan Membrane Equilibrium. 5
   • F. Explain the Helmholtz and Stern’s concept electrical double layer. 5
7. Q5 A) the blanks:- (Any five) h (second overtone, greater, microwave, rocking, waging, kgm’, As> Ai, 5 , As< Ki 1“ overtone) 5 marks
   • a. Unit for moment of inertia fora rotating molecule is
   • b. Out of plane vibration
   • c. In plane vibration
   • d. Molecules exhibit rotation spectra in region
   • e. In Stoke’s For an anharmonic oscillator, transition from v=0 to v=3 is called as
   • g. Rotational constant B =
   • h. Greater the value of force constant ‘K’, is the bond length State true or false:- (any five) 5
   • a. A Beckman thermometer is a differential thermometer
   • b. Van’t Hoff factor ‘i’ is always unity for non electrolytes
   • c. Ostwald & Walker method is used to determine lowering of vapor pressure
   • d. Osmotic pressure is not a colligative property
   • e. The freezing point of solvent will not change on addition of the solute
   • f. Lindemann’s theory is applicable to unimolecular reactions
   • g. Stop flow method is used to study the kinetics of slow reactions
   • h. When a chemical reaction obeys collision theory p=1 Fill in the blanks:- (any five) 5
   • a. In G-M counter, used as a quenching agent
   • b. The parent element which is bombarded with a fast moving particle is called
   • c. is a fissile material
   • d. is a fertile material
   • e. If fission reaction proceeds at a steady rate
   • f. Inabreeder reaction is converted into
   • g. are not effected by magnetic electric field Match the following: - (any five) 5 [Increases rate of

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