1. The analysis of electromagnetic radiation scattered, absorbed or emitted by the molecule is called __________
a) Kaleidoscopy
b) Astronomy
c) Spectroscopy
d) Anatomy
Answer: c
Explanation: The analysis of electromagnetic radiation scattered, absorbed or emitted by the molecule is called spectroscopy. Astronomy is the study of celestial objects and processes the physics, chemistry, and evolution of such objects and processes. A kaleidoscope is an optical instrument, typically a cylinder with mirrors containing loose, colored objects such as beads or pebbles and bits of glass. Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts.
2. The energy level with lower energy is called __________
a) Ground state energy level
b) Initial state energy level
c) Excited state energy level
d) All of the mentioned
Answer: a
Explanation: The lower energy level is called the ground state and the higher energy level is called excited state. The excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has higher energy than the ground state.
3. Absorption spectrum results when an electron in an atom undergoes a transition from __________
a) Higher energy level to a lower one
b) Lower energy level to a higher one
c) Intermediate levels
d) All of the mentioned
Answer: b
Explanation: Absorption spectrum results when an electron in an atom undergoes a transition from lower energy level to a higher one.
4. The energy of a photon is given by __________
a) h/ν
b) ν/h
c) 1/hν
d) hν
Answer: d
Explanation: The energy of a photon is given by hν where ν is the frequency and h is plank constant.
5. Select the incorrect statement from the following option.
a) Emission spectrum results when an electron in an atom undergoes a transition from excited state to the ground state
b) In the emission spectrum, transition takes place with the emission of a photon of energy hν
c) In the emission spectrum, transition takes place with the absorption of a photon of energy hν
d) All of the mentioned
Answer: c
Explanation: In the emission spectrum, transition takes place with the emission of a photon of energy hν. All the other options are correct. Emission spectrum results when an electron in an atom undergoes a transition from excited state to the ground state.
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6. The spectra can be broadly classified into two categories. They are __________
a) Atomic and molecular spectra
b) Atomic and electronic spectra
c) Molecular and electronic spectra
d) None of the mentioned
Answer: a
Explanation: The spectra can be broadly classified into two categories: atomic and molecular spectra. Atomic spectra are the spectrum of frequencies of electromagnetic radiation emitted or absorbed during transitions of electrons between energy levels within an atom. Molecular spectra arises from the transition of an electron between the molecular energy levels.
7. In atomic spectroscopy, only electronic transitions are involved.
a) True
b) False
Answer: a
Explanation: In atomic spectroscopy, only electronic transitions are involved. It is the spectrum of frequencies of electromagnetic radiation emitted or absorbed during transitions of electrons between energy levels within an atom.
8. Select the correct statement from the following options.
a) Molecular spectra arises from the transition of an electron between the molecular energy levels
b) In molecular transitions, electronic, rotational and vibration transitions occurs
c) Molecular spectra is more complicated than atomic spectra
d) All of the mentioned
Answer: d
Explanation: Molecular spectra arises from the transition of an electron between the molecular energy levels. In molecular transitions, electronic, rotational and vibration transitions occurs and molecular spectra is more complicated than atomic spectra.
9. The necessary condition for absorption spectrum is that __________
a) hν should be greater than the energy difference
b) hν should be smaller than the energy difference
c) hν should be equal to the energy difference
d) none of the mentioned
Answer: c
Explanation: The necessary condition for absorption spectrum is that hν should be equal to the energy difference(ΔE = Ee – Eg).
10. Spectroscopy deals with the transition that a molecule undergoes on the absorption of suitable radiations determined by quantum mechanical selection rules.
a) True
b) False
Answer: a
Explanation: Spectroscopy deals with the transition that a molecule undergoes on the absorption of suitable radiations determined by quantum mechanical selection rules. The spectra can be broadly classified into two categories: atomic and molecular spectra.
11. The different types of energies associated with a molecule are __________
a) Electronic energy
b) Vibrational energy
c) Rotational energy
d) All of the mentioned
Answer: d
Explanation: The different types of energies associated with a molecule are electronic energy, vibrational energy, rotational energy and translational energy.
12. During the motion, if the centre of gravity of molecule changes, the molecule possess __________
a) Electronic energy
b) Rotational energy
c) Translational energy
d) Vibrational energy
Answer: c
Explanation: During the motion, if the centre of gravity of molecule changes, the molecule possess translational energy. Translational refers to the movement in horizontal or vertical direction.
13. The region of electromagnetic spectrum for nuclear magnetic resonance is __________
a) Microwave
b) Radio frequency
c) Infrared
d) UV-rays
Answer: b
Explanation: The region of the electromagnetic spectrum for nuclear magnetic resonance is radio frequency.
14. Which of the following is an application of molecular spectroscopy?
a) Structural investigation
b) Basis of understanding of colors
c) Study of energetically excited reaction products
d) All of the mentioned
Answer: d
Explanation: The various applications of molecular spectroscopy are- Structural investigation, basis of understanding of colors and study of energetically excited reaction products.
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15. Select the correct statement from the following option.
a) Spectroscopic methods require less time and more amount of sample than classical methods
b) Spectroscopic methods require more time and more amount of sample than classical methods
c) Spectroscopic methods require less time and less amount of sample than classical methods
d) Spectroscopic methods require more time and less amount of sample than classical methods
Answer: c
Explanation: Spectroscopic methods require less time and less amount of sample than classical methods (1 mg).
16. The results obtained by spectroscopic methods are less reliable, less reproducible and incorrect than classical methods.
a) True
b) False
Answer: b
Explanation: The results obtained by spectroscopic methods are reliable, reproducible and correct than classical methods.
17. The transition zone for Raman spectra is __________
a) Between vibrational and rotational levels
b) Between electronic levels
c) Between magnetic levels of nuclei
d) Between magnetic levels of unpaired electrons
Answer: a
Explanation: The transition zone for Raman spectra is between vibrational and rotational levels. Raman spectroscopy is a spectroscopic technique used to observe vibrational, rotational, and other low-frequency modes in a system.
18. The criteria for electronic spin resonance is ____________
a) Periodic change in polarisability
b) Spin quantum number of nuclei > 0
c) Presence of unpaired electron in a molecule
d) Presence of chromophore in a molecule
Answer: c
Explanation: The criterion for electronic spin resonance is the presence of unpaired electron in a molecule. This spectroscopy is a method for studying materials with unpaired electrons.
19. Sample recovery is possible after spectroscopic analysis because the sample is not chemically affected.
a) True
b) False
Answer: a
Explanation: Sample recovery is possible after spectroscopic analysis because the sample is not chemically affected.
20. Which of the following is not an auxochrome group?
a) –OH
b) –SH
c) –OR
d) –O2
Answer: d
Explanation: Auxochrome is the color enhancing group. –O2 is not an example of auxochrome. -OH, -SH and -OR are examples of auxochrome.
21. Which of the following shift leads to the decreased intensity of absorption?
a) Hypochromic
b) Hyperchromic
c) Hypsochromic
d) Bathochromic
Answer: a
Explanation: Hypochromic shift leads to the decreased intensity of absorption. Hypochromicity describes a material’s decreasing ability to absorb light. Hyperchromicity is the material’s increasing ability to absorb light.
22. Which of the following is an application of electronic spectroscopy?
a) Detection of impurities
b) Control of purification
c) Study of kinetics of the chemical reaction
d) All of the mentioned
Answer: d
Explanation: Detection of impurities, control of purification, study of the kinetics of the chemical reaction, determination of molecular weight and determination of unknown concentration are the applications of electronic spectroscopy.
23. What will be the absorbance if %T = 80?
a) 0.5
b) 0.05
c) 0.097
d) 0.97
Answer: c
Explanation: Absorbance (A) = log(1/T) = log(100/80) = 0.097
24. Which of the following is a limitation of the Lambert-Beer’s law?
a) Scattering of light due to particles
b) Fluorescence of sample
c) Non-monochromatic radiation
d) All of the mentioned
Answer: d
Explanation: Scattering of light due to particles, fluorescence of the sample and non-monochromatic radiation are some of the limitations of Lambert-Beer’s law. It relates the attenuation of light to the properties of the material through which the light is traveling.
25. Which of the region of IR spectra appears between (1400-600) cm-1?
a) Functional group region
b) Fingerprint region
c) Low-frequency region
d) None of the mentioned
Answer: b
Explanation: Fingerprint region of IR spectra appears between (1400-600) cm-1.
26. Select the correct statement from the following option.
a) Infrared spectra can identify the unknown materials
b) It can determine the amount of components in a mixture
c) It can also determine the quality of a sample
d) All of the mentioned
Answer: d
Explanation: Infrared spectra can identify the unknown materials. It can determine the amount of components in a mixture and can also determine the quality of a sample.
27. Which of the following molecule have infrared active vibrations?
a) NO
b) CH4
c) H2
d) All of the mentioned
Answer: a
Explanation: NO molecule have infrared active vibrations. Infrared spectra can identify unknown materials. It can determine the amount of components in a mixture and can also determine the quality of a sample.
28. Which of the following cannot show a vibrational absorption spectrum?
a) OCS
b) H2O
c) CO2
d) C H2 = C H2
Answer: d
Explanation: C H2 = C H2 cannot show vibrational absorption spectrum. OCS, H2O and CO2 can show a vibrational absorption spectrum.
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29. Which of the following is not a type of bending molecular vibration?
a) Twisting
b) Stretching
c) Wagging
d) Rocking
Answer: b
Explanation: Stretching is not a type of bending molecular vibration. Twisting, wagging and rocking are types of bending molecular vibration.
30. What is the absorption frequency(cm-1) of –C=N functional group?
a) 3610-3640
b) 1690-1760
c) 1180-1360
d) 2850-2960
Answer: c
Explanation: The absorption frequency for –C=N group is 1180-1360 cm-1. Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample.
31. Presence of a functional group in a compound can be established by using _____________
a) Chromatography
b) IR spectroscopy
c) Mass spectroscopy
d) X-ray diffraction
Answer: b
Explanation: Presence of a functional group in a compound can be established by using IR spectroscopy. It is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light.
32. Select the incorrect option from the following option.
a) IR spectroscopy helps in the determination of purity
b) IR spectroscopy helps in the determination of force constant from vibrational spectrum
c) IR spectroscopy helps in identifying an unknown compound
d) None of the mentioned
Answer: d
Explanation: All the options are correct. IR spectroscopy helps in the determination of purity, force constant from the vibrational spectrum and identifying an unknown compound.
33. IR spectroscopy helps in detecting the presence of hydrogen bonding.
a) True
b) False
Answer: a
Explanation: IR spectroscopy helps in detecting the presence of hydrogen bonding. It is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light.
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