HSSC-II (Class-12) Solved Physics MCQs; Unit-19: Atomic Spectra; (New Book/KPK Text Board, Peshawar) With Verified Answers

1. Which of the following series of hydrogen spectra lies in the visible region of the spectrum

A. Layman
B. Balmer
C. Pashen
D. Brackett

... Answer is B. Balmer
--------------------------

2. The longest wavelength in Balmer's series with wavelength is 656.20 corresponds to

A. n = 3
B. n = 4
C. n = 5
D. n = ∞

... Answer is A. n = 3
----------------------

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

A. 10.2 eV
B. 0 eV
C. 3.4 eV
D. 6.8 eV

... Answer is C. 3.4 eV
---------------------------

4. If an atom exists in excited state n = 5, the maximum number of transitions that take place is

A. 3
B. 5
C. 10
D. 25

... Answer is C. 10
--------------------------------

5.  The energy of the electron in the excited state n = 4 in a hydrogen atom is

A. -13.6 eV
B. -3.4 eV
C. -0.85 eV
D. -1.5 eV

... Answer is C. -0.85 eV
------------------------

6. The radius of the third Bohr orbit is greater than the radius of the first Bohr orbit (Bohr's radius) by a factor of

A. 3
B. 6
C. 9
D. 16

... Answer is C. 9
------------------------------

7. The reverse process of X-ray production can be related to :

A. Compton Effect
B. Photoelectric effect
C. Pair Production
D. Pair Annihilation

... Answer is B. Photoelectric effect
--------------------------

8. The duration of the meta-stable state is approximately

A. 10⁻³ s
B. 10⁻⁶ s
C. 10⁻⁸ s
D. 10⁻¹⁰ s

... Answer is A. 10⁻³ s
-------------------------

9. Helium-Neon Laser beam emitted from a discharge tube has a color

A. Blue
B. Green
C. Red
D. White

... Answer is C. Red
------------------------

10. In He-Ne LASER, the discharged tube is filled with

A. 50 % He ＆ 50% Ne
B. 15% He ＆ 85 % Ne
C. 85% He ＆ 15% Ne
D. 99% He ＆ 1% Ne

... Answer is C. 85% He ＆ 15% Ne
----------------------

11. In neon, the 20.66-eV level can undergo lasing action to the 18.70-ev level. What is the energy of the resulting photons?

A. 20.66 eV
B. 18.70 eV
C. 39.36 eV
D. 1.96 eV

... Answer is D. 1.96 eV
------------------------------

12. In connection with the inner shell transition the symbol Lᵦ refers to x-ray emission associated with an electron going from

A. n = 3 to n = 1
B. n = 4 to n = 1
C. n = 4 to n = 2
D. n = 5 to n = 3

... Answer is C. n = 4 to n = 2
-------------------------

13. In laser the pumping is performed to

A. produce meta-stable states
B. produce stimulated emission
C. achieve population inversion
D. achieve coherency in photons

... Answer is C. achieve population inversion
: -------------------------

14.  Linear momentum of an electron in Bohr orbit of H-atom (principal quantum number n) is proportional to

A. n
B. 1/n
C. n²
D. 1/n²

... Answer is A. n
----------------------------

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