IGNOU MCH 20 SOLVED ASSIGNMENT

Ques 1.

Explain the origin of atomic spectrum.

Ques 2.

What is meant by anisotropy of chemical bond? Give an example.

Ques 3.

What makes TMS a molecule of choice to act as a reference in the NMR spectrometry?

Ques 4.

What is meant by polarizability of a molecule?

Ques 5.

In what way is NMR spectrometry different from other molecular spectroscopic methods?

Ques 6.

What is the importance of  spectroscopy in structure determination?

Ques 7.

 What is the requirement of the vibrational mode of a molecule to be Raman active?

Ques 8.

What is the photoelectric effect? Write the equation of Einstein’s photoelectric law.

Ques 9.

 5G services in India are provided at a frequency of . Calculate the wavelength of the radiation. 

Ques 10.

Explain why the atomic spectra are line spectra whereas the molecular spectra are band spectra. 

Ques 11.

A photon of visible light has a wavelength of . Calculate its 
(i) wavenumber
(ii) frequency
(iii) energy per mol

Ques 12.

 What is meant by the Balmer series of hydrogen? What will be the wave number of the longest wavelength in the Balmer series?

Ques 13.

 A photoelectron spectrum of a compound containing nitrogen (N), aluminium (Al), and fluorine (F) shows three strong peaks at the following binding energies:

Peak X: ~686 eV

Peak Y: ~399 eV

Peak Z: ~73 eV

Find the best option from the choices given below that best explains the relative positioning of these peaks in terms of binding energy.

(i) Peak X corresponds to F 1s electrons, which have the highest binding energy because fluorine’s high electronegativity and small size give its 1s electrons a large effective nuclear attraction. Peak Y is N 1s and Peak Z is Al 2p.

(ii) Nitrogen has more valence electrons than fluorine or aluminium, therefore its peak appears at the highest binding energy.

(iii) The spectrum shows more aluminium atoms than nitrogen or fluorine, so its peak appears at the lowest binding energy due to dilution.

(iv) Aluminium has the highest nuclear charge, so its 2p peak should have the largest binding energy, but shielding effects reverse this trend.
Justify your answer. 

Ques 14.

What information about the molecule can be obtained from a rotation spectrum? 

Ques 15.

What is meant by a selection rule? Give the selection rule for a rotating diatomic molecule modelled as a rigid rotator. 

Ques 16.

Assuming that the force constants of H-Cl and D-Cl are the same, calculate the fundamental vibration frequency of D-Cl if that of H-Cl is . 

Ques 17.

In Raman spectra, the Stokes line are more intense than the anti-Stokes lines. Why? 

Ques 18.

The rotational Raman spectrum of a diatomic molecule has the first line of a series of Stokes and anti-Stokes lines at , relative of the  of incident light. What would be its bond length. 

Ques 19.

 has bond length . Calculate the wavenumbers of the first four lines in its microwave spectrum. 

[Given: mass of C=12.000 u and mass of N=14.007 u]

Ques 20.

 Calculate the number of vibrational modes for a molecule of methane.

Ques 21.

The frequencies of the first and second overtones respectively are exactly double and triple of the fundamental vibration frequency. Comment. 

Ques 22.

Raman rotational spectra of  was observed with Hg light with Rayleigh line at . Stokes lines were observed at . Draw the rotational energy level diagram with Stokes and anti Stokes lines. 

Ques 23.

Electronic transitions are called vertical transitions. Comment. 

Ques 24.

A light source of wavelength  illuminates a metal surface and electron are ejected with the maximum kinetic energy 2 eV. If the same surface is illuminated by a light source of wavelength , then calculate the maximum kinetic energy of the ejected electron. (Work function of metal is 1 eV) 

Ques 25.

How does the rule of Mutual Exclusion help in predicting the symmetry in case of  and  molecules? 

Ques 26.

The molecule  has 3 fundamental vibrational frequencies. One is Raman active and two are IR active. Identify the structure of the molecule. 

Ques 27.

Explain why the  spin splitting is not observed in  spectrum? 

Ques 28.

Predict the number of signal and multiplicity of peaks in the  spectrum of the following compounds: 

a) 2,5-Dimethylhexane

b) Cyclohexanol

Ques 29.

What is meant by AX spin system in NMR? Draw a schematic energy level diagram for this system and show the allowed transitions. 

Ques 30.

Calculate the ESR frequency of an unpaired electron in a magnetic field of 3000 G (0.3 T). 

[Given: ; ; and ]

Ques 31.

Which of the following systems will show electron spin resonance (ESR) spectrum? (i) H (ii)  (iii)  (iv)  (v)  (vi)  

Ques 32.

What are different mechanisms that contribute to the relaxation of nuclear spins in the excited state? Explain any one of them.

Ques 33.

 What is Mossbauer effect? 

Ques 34.

The lifetime of  (excited state) is . If the excited state is  above the ground state determine the linewidth  and ratio . 

Ques 35.

Isomer shift

Ques 36.

Spin-Spin splitting

Ques 37.

 Explain the origin of atomic spectrum.

Ques 38.

What is meant by anisotropy of chemical bond? Give an example.

Ques 39.

What makes TMS a molecule of choice to act as a reference in the NMR spectrometry?

Ques 40.

 What is meant by polarizability of a molecule?

Ques 41.

In what way is NMR spectrometry different from other molecular spectroscopic methods?

Ques 42.

What is the importance of  spectroscopy in structure determination?

Ques 43.

What is the requirement of the vibrational mode of a molecule to be Raman active?

Ques 44.

What is the photoelectric effect? Write the equation of Einstein’s photoelectric law.

Ques 45.

 5G services in India are provided at a frequency of . Calculate the wavelength of the radiation. 

Ques 46.

Explain why the atomic spectra are line spectra whereas the molecular spectra are band spectra. 

Ques 47.

 A photon of visible light has a wavelength of . Calculate its 
(i) wavenumber
(ii) frequency
(iii) energy per mol

Ques 48.

What is meant by the Balmer series of hydrogen? What will be the wave number of the longest wavelength in the Balmer series?

Ques 49.

A photoelectron spectrum of a compound containing nitrogen (N), aluminium (Al), and fluorine (F) shows three strong peaks at the following binding energies:
Peak X: ~686 eV
Peak Y: ~399 eV
Peak Z: ~73 eV

Find the best option from the choices given below that best explains the relative positioning of these peaks in terms of binding energy.

Ques 50.

Peak X corresponds to F 1s electrons, which have the highest binding energy because fluorine’s high electronegativity and small size give its 1s electrons a large effective nuclear attraction. Peak Y is N 1s and Peak Z is Al 2p.

Ques 51.

Nitrogen has more valence electrons than fluorine or aluminium, therefore its peak appears at the highest binding energy.

Ques 52.

The spectrum shows more aluminium atoms than nitrogen or fluorine, so its peak appears at the lowest binding energy due to dilution.

Ques 53.

Aluminium has the highest nuclear charge, so its 2p peak should have the largest binding energy, but shielding effects reverse this trend.
Justify your answer. 

Ques 54.

What information about the molecule can be obtained from a rotation spectrum? 

Ques 55.

What is meant by a selection rule? Give the selection rule for a rotating diatomic molecule modelled as a rigid rotator. 

Ques 56.

 Assuming that the force constants of H-Cl and D-Cl are the same, calculate the fundamental vibration frequency of D-Cl if that of H-Cl is . 

Ques 57.

 In Raman spectra, the Stokes line are more intense than the anti-Stokes lines. Why? 

Ques 58.

 The rotational Raman spectrum of a diatomic molecule has the first line of a series of Stokes and anti-Stokes lines at , relative of the  of incident light. What would be its bond length. 

Ques 59.

 has bond length . Calculate the wavenumbers of the first four lines in its microwave spectrum. 
[Given: mass of C=12.000 u and mass of N=14.007 u]

Ques 60.

 Calculate the number of vibrational modes for a molecule of methane.

Ques 61.

The frequencies of the first and second overtones respectively are exactly double and triple of the fundamental vibration frequency. Comment. 

Ques 62.

 Raman rotational spectra of  was observed with Hg light with Rayleigh line at . Stokes lines were observed at . Draw the rotational energy level diagram with Stokes and anti Stokes lines. 

Ques 63.

Electronic transitions are called vertical transitions. Comment. 

Ques 64.

A light source of wavelength  illuminates a metal surface and electron are ejected with the maximum kinetic energy 2 eV. If the same surface is illuminated by a light source of wavelength , then calculate the maximum kinetic energy of the ejected electron. (Work function of metal is 1 eV) 

Ques 65.

 How does the rule of Mutual Exclusion help in predicting the symmetry in case of  and  molecules? 

Ques 66.

The molecule  has 3 fundamental vibrational frequencies. One is Raman active and two are IR active. Identify the structure of the molecule. 

Ques 67.

Explain why the  spin splitting is not observed in  spectrum? 

Ques 68.

Predict the number of signal and multiplicity of peaks in the  spectrum of the following compounds: 
a) 2,5-Dimethylhexane
b) Cyclohexanol

Ques 69.

What is meant by AX spin system in NMR? Draw a schematic energy level diagram for this system and show the allowed transitions. 

Ques 70.

Calculate the ESR frequency of an unpaired electron in a magnetic field of 3000 G (0.3 T). 
[Given: ; ; and ]

Ques 71.

Which of the following systems will show electron spin resonance (ESR) spectrum? (i) H (ii)  (iii)  (iv)  (v)  (vi)  

Ques 72.

 What are different mechanisms that contribute to the relaxation of nuclear spins in the excited state? Explain any one of them.

Ques 73.

What is Mossbauer effect? 

Ques 74.

 The lifetime of  (excited state) is . If the excited state is  above the ground state determine the linewidth  and ratio . 

Ques 75.

Write short notes on the following. 

Ques 76.

 Isomer shift (b) Spin-Spin splitting

Ques 77.

Explain the origin of atomic spectrum.

Ques 78.

What is meant by anisotropy of chemical bond? Give an example.

Ques 79.

What makes TMS a molecule of choice to act as a reference in the NMR spectrometry?

Ques 80.

What is meant by polarizability of a molecule?

Ques 81.

In what way is NMR spectrometry different from other molecular spectroscopic methods?

Ques 82.

What is the importance of  spectroscopy in structure determination?

Ques 83.

 What is the requirement of the vibrational mode of a molecule to be Raman active?

Ques 84.

What is the photoelectric effect? Write the equation of Einstein’s photoelectric law.

Ques 85.

 5G services in India are provided at a frequency of . Calculate the wavelength of the radiation. 

Ques 86.

Explain why the atomic spectra are line spectra whereas the molecular spectra are band spectra. 

Ques 87.

A photon of visible light has a wavelength of . Calculate its 
(i) wavenumber
(ii) frequency
(iii) energy per mol

Ques 88.

 What is meant by the Balmer series of hydrogen? What will be the wave number of the longest wavelength in the Balmer series?

Ques 89.

 A photoelectron spectrum of a compound containing nitrogen (N), aluminium (Al), and fluorine (F) shows three strong peaks at the following binding energies:

Peak X: ~686 eV

Peak Y: ~399 eV

Peak Z: ~73 eV

Find the best option from the choices given below that best explains the relative positioning of these peaks in terms of binding energy.

(i) Peak X corresponds to F 1s electrons, which have the highest binding energy because fluorine’s high electronegativity and small size give its 1s electrons a large effective nuclear attraction. Peak Y is N 1s and Peak Z is Al 2p.

(ii) Nitrogen has more valence electrons than fluorine or aluminium, therefore its peak appears at the highest binding energy.

(iii) The spectrum shows more aluminium atoms than nitrogen or fluorine, so its peak appears at the lowest binding energy due to dilution.

(iv) Aluminium has the highest nuclear charge, so its 2p peak should have the largest binding energy, but shielding effects reverse this trend.
Justify your answer. 

Ques 90.

What information about the molecule can be obtained from a rotation spectrum? 

Ques 91.

What is meant by a selection rule? Give the selection rule for a rotating diatomic molecule modelled as a rigid rotator. 

Ques 92.

Assuming that the force constants of H-Cl and D-Cl are the same, calculate the fundamental vibration frequency of D-Cl if that of H-Cl is . 

Ques 93.

In Raman spectra, the Stokes line are more intense than the anti-Stokes lines. Why? 

Ques 94.

The rotational Raman spectrum of a diatomic molecule has the first line of a series of Stokes and anti-Stokes lines at , relative of the  of incident light. What would be its bond length. 

Ques 95.

 has bond length . Calculate the wavenumbers of the first four lines in its microwave spectrum. 

[Given: mass of C=12.000 u and mass of N=14.007 u]

Ques 96.

 Calculate the number of vibrational modes for a molecule of methane.

Ques 97.

The frequencies of the first and second overtones respectively are exactly double and triple of the fundamental vibration frequency. Comment. 

Ques 98.

Raman rotational spectra of  was observed with Hg light with Rayleigh line at . Stokes lines were observed at . Draw the rotational energy level diagram with Stokes and anti Stokes lines. 

Ques 99.

Electronic transitions are called vertical transitions. Comment. 

Ques 100.

A light source of wavelength  illuminates a metal surface and electron are ejected with the maximum kinetic energy 2 eV. If the same surface is illuminated by a light source of wavelength , then calculate the maximum kinetic energy of the ejected electron. (Work function of metal is 1 eV) 

Ques 101.

How does the rule of Mutual Exclusion help in predicting the symmetry in case of  and  molecules? 

Ques 102.

The molecule  has 3 fundamental vibrational frequencies. One is Raman active and two are IR active. Identify the structure of the molecule. 

Ques 103.

Explain why the  spin splitting is not observed in  spectrum? 

Ques 104.

Predict the number of signal and multiplicity of peaks in the  spectrum of the following compounds: 

a) 2,5-Dimethylhexane

b) Cyclohexanol

Ques 105.

What is meant by AX spin system in NMR? Draw a schematic energy level diagram for this system and show the allowed transitions. 

Ques 106.

Calculate the ESR frequency of an unpaired electron in a magnetic field of 3000 G (0.3 T). 

[Given: ; ; and ]

Ques 107.

Which of the following systems will show electron spin resonance (ESR) spectrum? (i) H (ii)  (iii)  (iv)  (v)  (vi)  

Ques 108.

What are different mechanisms that contribute to the relaxation of nuclear spins in the excited state? Explain any one of them.

Ques 109.

 What is Mossbauer effect? 

Ques 110.

The lifetime of  (excited state) is . If the excited state is  above the ground state determine the linewidth  and ratio . 

Ques 111.

Isomer shift

Ques 112.

Spin-Spin splitting

Ques 113.

 Explain the origin of atomic spectrum.

Ques 114.

What is meant by anisotropy of chemical bond? Give an example.

Ques 115.

What makes TMS a molecule of choice to act as a reference in the NMR spectrometry?

Ques 116.

 What is meant by polarizability of a molecule?

Ques 117.

In what way is NMR spectrometry different from other molecular spectroscopic methods?

Ques 118.

What is the importance of  spectroscopy in structure determination?

Ques 119.

What is the requirement of the vibrational mode of a molecule to be Raman active?

Ques 120.

What is the photoelectric effect? Write the equation of Einstein’s photoelectric law.

Ques 121.

 5G services in India are provided at a frequency of . Calculate the wavelength of the radiation. 

Ques 122.

Explain why the atomic spectra are line spectra whereas the molecular spectra are band spectra. 

Ques 123.

 A photon of visible light has a wavelength of . Calculate its 
(i) wavenumber
(ii) frequency
(iii) energy per mol

Ques 124.

What is meant by the Balmer series of hydrogen? What will be the wave number of the longest wavelength in the Balmer series?

Ques 125.

A photoelectron spectrum of a compound containing nitrogen (N), aluminium (Al), and fluorine (F) shows three strong peaks at the following binding energies:
Peak X: ~686 eV
Peak Y: ~399 eV
Peak Z: ~73 eV

Find the best option from the choices given below that best explains the relative positioning of these peaks in terms of binding energy.

Ques 126.

Peak X corresponds to F 1s electrons, which have the highest binding energy because fluorine’s high electronegativity and small size give its 1s electrons a large effective nuclear attraction. Peak Y is N 1s and Peak Z is Al 2p.

Ques 127.

Nitrogen has more valence electrons than fluorine or aluminium, therefore its peak appears at the highest binding energy.

Ques 128.

The spectrum shows more aluminium atoms than nitrogen or fluorine, so its peak appears at the lowest binding energy due to dilution.

Ques 129.

Aluminium has the highest nuclear charge, so its 2p peak should have the largest binding energy, but shielding effects reverse this trend.
Justify your answer. 

Ques 130.

What information about the molecule can be obtained from a rotation spectrum? 

Ques 131.

What is meant by a selection rule? Give the selection rule for a rotating diatomic molecule modelled as a rigid rotator. 

Ques 132.

 Assuming that the force constants of H-Cl and D-Cl are the same, calculate the fundamental vibration frequency of D-Cl if that of H-Cl is . 

Ques 133.

 In Raman spectra, the Stokes line are more intense than the anti-Stokes lines. Why? 

Ques 134.

 The rotational Raman spectrum of a diatomic molecule has the first line of a series of Stokes and anti-Stokes lines at , relative of the  of incident light. What would be its bond length. 

Ques 135.

 has bond length . Calculate the wavenumbers of the first four lines in its microwave spectrum. 
[Given: mass of C=12.000 u and mass of N=14.007 u]

Ques 136.

 Calculate the number of vibrational modes for a molecule of methane.

Ques 137.

The frequencies of the first and second overtones respectively are exactly double and triple of the fundamental vibration frequency. Comment. 

Ques 138.

 Raman rotational spectra of  was observed with Hg light with Rayleigh line at . Stokes lines were observed at . Draw the rotational energy level diagram with Stokes and anti Stokes lines. 

Ques 139.

Electronic transitions are called vertical transitions. Comment. 

Ques 140.

A light source of wavelength  illuminates a metal surface and electron are ejected with the maximum kinetic energy 2 eV. If the same surface is illuminated by a light source of wavelength , then calculate the maximum kinetic energy of the ejected electron. (Work function of metal is 1 eV) 

Ques 141.

 How does the rule of Mutual Exclusion help in predicting the symmetry in case of  and  molecules? 

Ques 142.

The molecule  has 3 fundamental vibrational frequencies. One is Raman active and two are IR active. Identify the structure of the molecule. 

Ques 143.

Explain why the  spin splitting is not observed in  spectrum? 

Ques 144.

Predict the number of signal and multiplicity of peaks in the  spectrum of the following compounds: 
a) 2,5-Dimethylhexane
b) Cyclohexanol

Ques 145.

What is meant by AX spin system in NMR? Draw a schematic energy level diagram for this system and show the allowed transitions. 

Ques 146.

Calculate the ESR frequency of an unpaired electron in a magnetic field of 3000 G (0.3 T). 
[Given: ; ; and ]

Ques 147.

Which of the following systems will show electron spin resonance (ESR) spectrum? (i) H (ii)  (iii)  (iv)  (v)  (vi)  

Ques 148.

 What are different mechanisms that contribute to the relaxation of nuclear spins in the excited state? Explain any one of them.

Ques 149.

What is Mossbauer effect? 

Ques 150.

 The lifetime of  (excited state) is . If the excited state is  above the ground state determine the linewidth  and ratio . 

Ques 151.

Write short notes on the following. 

Ques 152.

 Isomer shift (b) Spin-Spin splitting

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