K.S ACADEMY, SALEM-QUESTION PAPER PG TRB, POLYTECHNIC TRB & TNSET. COACHING CENTRE FOR PHYSICS Slip test- Spectroscopy

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1 PG TRB, POLYTECHNIC TRB & TNSET COACHING CENTRE FOR PHYSICS Slip test- Spectroscopy Time:1Hour Marks: 40 ************************************************************************ Answer all the question: 1.The frequency of the Raman stoke equation is represented by the following equation a)υ = υ 0 + E h b) υ = υ 0 E h c) υ 2 = υ 0 E h d)υ = υ 0 2.In the rotational spectrum of the diatomic molecule a)frequency lines are not equally spaced b)frequency lines are equally spaced c)energy levels are equally spaced d)energy difference two consecutive energy levels are equal 3.The lowest energy of vibrational rotational spectra is a) BJ J + 1 b) v hω c) 2B d) hν 2 4.In the case of stoke s line observed in Raman effect, the frequency of the line is a)less than that of the incident radiation b)more than that of the incident radiation c)equal to that of the incident radiation d) any of these PHYSICS CELL: Page 1

2 5. Pure rotation spectra lie in the a)near the infrared region c)visible region b)far infrared region d)ultraviolet region 6. Which quantum number were used by Sommerfield in order to explain the fine structure of spectral lines? a) n and l b) n and s c) l and s d) m l and m s 7.Which of the following is the selection rule for fundamental band? a) υ = ±2 b) υ = 0, ±1 c) υ = ±1 d) υ = ±3 8.For rotational spectrum a)energy levels are not equally spaced but frequency is equally spaced b)energy and frequency are equally spaced c)both the energy and frequency are not equally spaced d)energy levels are equally spaced but frequency levels are not equally spaced 9.For which of the following can both quantum number and the associated energy be zero? a) n for the particle in a 1-D box b) J for the rigid rotator c) v for harmonic oscillator d) n for hydrogen atom 10. The relation between wavelength and wave number is a) v = 1 λ b) v = λ c) v = 2λ d) all the above 11.The value of n 2 corresponding to minimum and maximum wavelength in Balmer series are respectively a) 3 and b) 3 and 0 c) 0 and3 d) and 3 PHYSICS CELL: Page 2

3 12.Pure vibrational spectra are observed a)only in solids c)only in gases b)only in liquids d)both in liquids & gases 13. A linear molecule of N atoms has vibrational degrees of freedom a) 3N 5 b) 3N 6 c) 3N d) 3N 4 14.The symmetric stretching mode of vibration of CO2 is a) Raman active b) Raman inactive c) IR active d) both Raman & IR active 15. A simplest diatomic molecule (e.g. H 2, O 2, CO, HCl ) may be considered as two point masses m 1 and m 2 connected by a spring like force. Such a molecule can vibrate along the line joining the atoms and may be considered as a two-body oscillator. The frequency of vibration of this oscillator is given by 3 a) v = 1 k b) v = 1 k c) v = 1 k 2 d) v = 1 k 2 2π μ 2π μ 2π μ 2π μ 16.The possible values of orbital quantum number are a) from 0 to (n-1) b) from 0 to n c) from 0 to (n+1) d) all 17.In rotational Raman spectrum what is the selection rule for Rayleigh line a) J = 1 b) J = 1 c) J = +2 d) J = 0 18.The convergence limit of the Lyman series is a) ν = R b) ν = R 4 c) ν = 3R 4 d) ν = 4 3R PHYSICS CELL: Page 3

4 19.The 3 principal moment of inertia of a spherical top is a) I B = I c > I A b) I B = I c < I A c) I B = I c, I A = 0 d) I A = I B = I C 20.In rotational Raman spectrum the Raman shift of stokes lines are a)2b, 4B, 6B b) 6B, 10B, 14B, c) -2B, -4B, -6B, d)2b, 6B, 12B, 21.In which of the following transitions of an electron in hydrogen atom the energy variation is minimum? a) from n=5 to n=4 b) from n=3 to n=2 C) from n=2 to n=1 d) from n=4 to n=3 22.The rotational kinetic energy of a rigid diatomic molecule is a) E = ħ2 2 ħ J J + 1 b) E = J J + 1 2I 8π 2 IC c) E = ħ2 2 ħ J J + 1 d) E = J J + 1 2π 2 IC 8π Globar source is a)ir source b)microwave source c)uv source d)x-ray source 24. Which of the following is/are true? a)rotational energy level is BJ(J + 1) b)the vibrational-rotation spectra fall in the infrared region. c)various electronic state do not have any systematic separation for a given molecule d) all the above PHYSICS CELL: Page 4

5 25.In vibrational spectra which of the following transistion most intense a) ν " = 0 ν = 2 b) ν " = 0 ν = 1 c) ν " = 0 ν = 3 d) ν " = 0 ν = 4 26.The change in energy in an electronic transistion is of the order of a) 0.1 ev b) ev c) 5 10 ev d) 20KeV 20 MeV 27. Why N 2, O 2, F 2 etc does not show a rotational spectrum? a) no rotation b) no diffraction c) no permanent dipole moment d) no vibration PROBLEM FOR POLYTECHNIC TRB( 2 mark question) 28. In a NMR spectrometer, the resonance transistion is shifted from the reference (400MHz) by 529 Hz, and then its chemical shift is a) 5.2 b) 2.0 c) 10.5 d) A sample was excited by 4358 Å line of Hg. One Raman line is observed at 4447 Å then the other associated a) 4325Å b)4269 Å c)4516 Å d)4482 Å 30. The ratio of minimum wavelengths of Lyman and Balmer series will be a) 1.25 b) 0.25 c)0.5 d) If the mass of electron is reduced to half, then the Rydberg constant is a) Remains unchanged b) Becomes half c) Becomes double d) Becomes one-fourth PHYSICS CELL: Page 5

6 32. In symmetric stretching mode of CO 2 a) both Raman and IR are active b) Raman inactive & IR active c) both Raman and IR are inactive d) Raman active & IR inactive 33. The force constant K of the bond in CO is 187 N/m. The spacing between its vibrational energy level is (reduced mass of CO is ) a) 8.44 ev b) 84.4 ev c) 844eV d) eV 34. The harmonic vibrational frequency of HCl in wavenumbers is cm 1 then the energies of the first vibrational levels in Joules a) J b) J c) J d) J. 35. The energy gap between the two vibrational levels of a hole molecule is 0.36ev then its zero point energy will be a)0.18ev b)0.36ev c)0.09ev d)0.72ev 36. The number of normal modes in SO 2 is a) 6 b) 4 c) 3 d) The no of fundamental vibrational model of co 2 molecule is a)four ;two are Raman active and two are infrared active b)four ;one is Raman active and three are infrared active c)three; one is Raman active and two are infrared active PHYSICS CELL: Page 6

7 d)three; two are Raman active and one is infrared active 38. The wavelength of Lyman series line due to the transistion from n = 2 to n = 1 is a) 12nm b) 1.2nm c) 120nm d) 1200nm 39. For HF molecule, v = 4050 m 1, rotational constant is half and moment of intertia I = 1.38 x kg-m 2 the internuclear distance r is a) 0.94 A b) 0.19 A c) 0.54 A d) 1.94 A 40. In a weak field the sodium D, (5896 Å) and D 2 (5290Å) are split into and lines respectively a) 6, 4 b) 3, 6 c) 4, 6 d) 6, 3 ANSWER KEY GIVEN AT THE LAST PAGE **************************************************************************************** ங கள ம ச சனம அபச ள ஆச ர னப க & ட க க வ ர வ ரபன ப க ண ன ற K.S அக ந ன ல இரணந த னன டற வ ர! (Exclusively for PHYSICS) TRB த ர வ ல ம ல ப பபண பபற ம ற ற ம TRB த ர வ ல அன பவம க க தப ச ர ரக பக ண ட நடத ப பட க மத. PHYSICS CELL: Page 7

8 ஒவ பவ ர UNIT க க ம SLIP TEST, UNIT TEST நடத ப பட ம. ஒவ பவ ர UNIT க க ம 400 தகள வ கள பக ட க கப பட ம னந த ற ம த ர வ கள நடத ப பட ம. 1/3 rd PORTION TEST, HALF PORTION TEST நடத ப பட ம. பத த ம ழ த ர வ கள (TEN FULL TEST) நடத ப பட ம. ப த க 4000 வ ன க கரர பக ட த த ப ற ச அர க கப பட ம ஆம ஆண ட ம ல நரடபபற ம PG TRB வ ன க கள பக ட க கப பட ம ஆம ஆண ட ம ல நரடபபற ம ப ய படக ன க, DIET வ ர வ ர ரர ற ற ம பப ம ல கல ல ர தப ச ர ர (Polytechnic, DIET & Engineering TRB ) வ ன க கள பக ட க கப பட ம. TNPSC நடத பள ர இரங கரய ஆச ர ர (BT SCHOOL ASST ) வ ன க கர ல PG TRB SYLLABUS வ டன ப டர ப ரட வ ன க கள பக ட க கப பட ம. தல ம இந ப ற ச வக ப ப ல கயந த பக ள வத TNSET, DIET LECTURER TRB & ENGINEERING ASSISTANT PROFESSOR TRB, SCIENTIFIC ASSISTANT (TNPSC ), DEO (TNPSC MAINS PAPER -3), TNPSC SCHOOL ASSISTANT த ர வ கலக க பன பட ம. EDUCATION, PSYCHOLOGY & GK வ ற க ன க அன பவம க க ஆச ர ரக பக ண ட ப ற ச பக ட க கப பட ம Your time is limited, so don t waste it. PHYSICS CELL: Page 8

9 வ ங க பட க கய ம! ப ற ச பபமய ம!! பவற ம ந ச சம!!! ம தல வக ப ப கள ஆபம ம K.S ACADEMY ச ப ப ர ர ட தட ர ல க தயஜ ப ல ட ங (STC ) டவ ன ல தவ ஸ தடஷன அர க ல தசயம ம தல வக ப ப கள ஆபம ம அர வ ரன பன ப உரதவ கர வ ன க யம அம ந த பச ன.... ர க க மள Answer key Q.NO ANS Q.NO ANS Q.NO ANS Q.NO ANS 1 B 11 D 21 A 31 B 2 B 12 B 22 C 32 D 3 D 13 A 23 A 33 D 4 A 14 A 24 D 34 D 5 B 15 A 25 B 35 A 6 A 16 A 26 C 36 C 7 C 17 D 27 C 37 B 8 A 18 A 28 D 38 C 9 B 19 D 29 B 39 A 10 A 20 B 30 B 40 C PHYSICS CELL: Page 9