Physics Quiz On Thermodynamics For B.Sc. Students

1.

If 13.6 eV energy is required to ionise the hydrogen atom, then energy required to remove an electron from n = 2 is

A.

3.4 eV
B.

0 eV
C.

.4 eV
D.

6.8 eV.

Correct Answer
A. 3.4 eV

Explanation
The energy required to remove an electron from the n = 2 energy level in the hydrogen atom can be calculated using the formula E = 13.6/n^2, where E is the energy in eV and n is the principal quantum number. Plugging in n = 2, we get E = 13.6/2^2 = 13.6/4 = 3.4 eV. Therefore, the energy required to remove an electron from n = 2 is 3.4 eV.

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2.

In Bohr’s model of an atom which of the following is an integral multiple of h/2π?

A.

Angular momentum
B.

Potential energy
C.

Radius of an atom
D.

Kinetic energy

Correct Answer
A. Angular momentum

Explanation
In Bohr's model of an atom, the angular momentum of an electron is quantized and can only take on certain specific values. These values are given by an integral multiple of h/2π, where h is Planck's constant. Therefore, the angular momentum is the only option among the given choices that can be an integral multiple of h/2π.

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3.

The K.E. of the electron in an orbit of radius r in hydrogen atom is proportional to

A.

E^(2)/r
B.

E^(4)/r
C.

2e^(2)/r
D.

E^(2)/2r

Correct Answer
A. E^(2)/r

Explanation
The correct answer is e^(2)/r. The kinetic energy (K.E.) of an electron in an orbit of radius r in a hydrogen atom is proportional to e^(2)/r. This is because the kinetic energy of a particle is directly proportional to its charge (e) squared and inversely proportional to its distance (r) from the center of the orbit. Therefore, as the radius decreases, the kinetic energy increases.

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4.

The different types of energies associated with a molecule are __________

A.

Electronic energy
B.

Vibrational energy
C.

Rotational energy
D.

All of the mentioned

Correct Answer
D. All of the mentioned

Explanation
All of the mentioned types of energies are associated with a molecule. Electronic energy refers to the energy associated with the movement of electrons within the molecule. Vibrational energy refers to the energy associated with the vibration of atoms within the molecule. Rotational energy refers to the energy associated with the rotation of the molecule as a whole. Therefore, all of these energies are present and contribute to the overall energy of a molecule.

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5.

The correct order of different types of energies is __________

A.

E_el >> E_vib >> E_rot >> E _tr
B.

E_el >> E_rot >> E_vib >> E _tr
C.

E_el >> E_vib >> E_tr >> E _rot
D.

E<sub style="font-variant-ligatures:normal; font-variant-caps:normal; orphans:2; widows:2; -webkit-text-stroke-width:0px; text-decoration-style:initial; text-decoration-color:initial; word-spacing:0px">tr >> E<sub style="font-variant-ligatures:normal; font-variant-caps:normal; orphans:2; widows:2; -webkit-text-stroke-width:0px; text-decoration-style:initial; text-decoration-color:initial; word-spacing:0px">vib >> E<sub style="font-variant-ligatures:normal; font-variant-caps:normal; orphans:2; widows:2; -webkit-text-stroke-width:0px; text-decoration-style:initial; text-decoration-color:initial; word-spacing:0px">rot >> E <sub style="font-variant-ligatures:normal; font-variant-caps:normal; orphans:2; widows:2; -webkit-text-stroke-width:0px; text-decoration-style:initial; text-decoration-color:initial; word-spacing:0px">el

Correct Answer
A. E_el >> E_vib >> E_rot >> E _tr

Explanation
The correct order of different types of energies is Eel (electrical energy) >> Evib (vibrational energy) >> Erot (rotational energy) >> E tr (translational energy). This order represents the hierarchy of energy types, with electrical energy being the highest in the hierarchy, followed by vibrational energy, rotational energy, and finally translational energy.

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6.

The transition zone for Raman spectra is __________

A.

Between magnetic levels of unpaired electrons
B.

Between magnetic levels of nuclei
C.

Between electronic levels
D.

Between vibrational and rotational levels

Correct Answer
D. Between vibrational and rotational levels

Explanation
The transition zone for Raman spectra is between vibrational and rotational levels. Raman spectroscopy is a technique that involves the interaction of light with molecules, causing a shift in energy levels. The energy levels of molecules can be categorized into electronic, vibrational, and rotational levels. In Raman spectroscopy, the transition zone refers to the energy range where transitions occur between the vibrational and rotational levels of the molecule. This transition zone is important in Raman spectroscopy as it provides information about the molecular structure and dynamics.

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7.

Solar cell works based on

A.

Laser technology
B.

Tyndall effect
C.

Photo-conduction
D.

Thermal emission

Correct Answer
C. pHoto-conduction

Explanation
Solar cells work based on the principle of photo-conduction. Photo-conduction refers to the process where the absorption of light by a material generates electric charges, leading to the flow of current. In solar cells, photons from sunlight are absorbed by a semiconductor material, such as silicon, creating electron-hole pairs. These charges then separate at the junction of different materials within the solar cell, creating a voltage difference and generating an electric current. Therefore, photo-conduction is the correct explanation for how solar cells convert sunlight into electricity.

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8.

Luminescence is because of

A.

Photons emitted while excited electrons drops down
B.

Knocking out of electrons by photons
C.

Photons stimulated by photons
D.

All

Correct Answer
A. pHotons emitted while excited electrons drops down

Explanation
When an electron is excited to a higher energy level, it can drop back down to its original energy level. During this process, it releases energy in the form of photons, which are particles of light. This phenomenon is known as luminescence. Therefore, the correct answer is "Photons emitted while excited electrons drops down."

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9.

Visible light’s wavelength range ______________

A.

0.39 – 0.77 mm
B.

0.39 – 0.77 µm
C.

0.39 – 0.77 nm
D.

0.39 – 0.77 cm
E.

Option 5

Correct Answer
A. 0.39 – 0.77 mm

Explanation
Visible light's wavelength range is typically measured in nanometers, not millimeters. The correct answer is 0.39 – 0.77 μm, which represents the range of wavelengths for visible light.

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10.

Proton has the charge

A.

1637 times of an electron
B.

1737 times of an electron
C.

1837 times of an electron
D.

1937 times of an electron

Correct Answer
C. 1837 times of an electron

Explanation
The charge of a proton is 1837 times greater than the charge of an electron.

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