Free MCQs & Online Quiz Practice for Exams

Q: 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

Q: The energy of the electron in the excited state n=4 in hydrogen atom is:

A) -0.85 eV

B) -1.5 eV

C) -3.4 eV

D) -13.6 eV

Q: The radius of the third Bohr orbit is greater than the radius of the first Bohr orbit by a factor of:

A) 3

B) 6

C) 9

D) 16

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

A) Compton effect

B) Photoelectric effect

C) Pair Production

D) Pair Annihilation

Q: The duration of a meta-stable state is approximately:

A) 10⁻³ s

B) 10⁶ s

C) 10⁸ s

D) 10¹⁰ s

Q: Helium-Neon laser beam emitted from a discharge tube has a color:

A) Blue

B) Green

C) Red

D) White

Q: The He-Ne discharge tube is filled with:

A) 50% He & 50% Ne

B) 15% He & 85% Ne

C) 85% He & 15% Ne

D) 99% He & 1% Ne

Q: 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

Q: In connection with inner shell transition, the symbol L 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

Q: In a laser the pumping is performed to:

A) Produce meta-stable states

B) Produce stimulated emission

C) Achieve population inversion

D) Achieve coherency in photons

Q: 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

Q: One unified mass scale (1 u) is equal to:

A) 1.660 × 10⁻²⁷ kg

B) 1.4924 × 10⁻¹⁰ J

C) 931.5 MeV

D) All of these

Q: The number of neutrons in ⁷Li are:

A) 7

B) 4

C) 3

D) 2

Q: Sum of the masses of constituent nucleons as compared to the mass of the resultant nucleus is:

A) Smaller

B) Greater

C) Same

D) Infinite

Q: Which one of the following nuclear radiations is similar to electrons:

A) α

B) β⁺

C) β⁻

D) γ

Q: One curie is equal to:

A) 3.70 × 10¹⁰ Bq

B) 1 MBq

C) 1 × 10¹⁰ Bq

D) 3.70 × 10¹⁰ Bq

Q: Half-life of iodine-131 (¹³¹I) is 8.02 days and its weight is 20 mg. After 4 half-lives, the amount left un-decayed will be:

A) 5 mg

B) 2.5 mg

C) 1.25 mg

D) 0.625 mg

Q: The unit of decay constant λ is:

A) m⁻¹

B) m²

C) s

D) s⁻¹

Q: In fission of ²³⁵U, neutrons used have energies of about:

A) 5 MeV

B) 0.6 keV

C) 8.6 eV

D) 0.04 eV

Q: The quantity of ²³⁵U in naturally occurring uranium is about:

A) 0.7%

B) 30%

C) 70%

D) 99.3%