Engineering Chemistry MCQ (Origin of spectrum)

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Engineering Chemistry MCQ (Origin of spectrum)

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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.

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.