Free MCQs & Online Quiz Practice for Exams

Q: The work function of a metal is 6.63 eV. Its threshold frequency is (ET 2012)

A) 1.6×10¹⁵ Hz

B) 1.6×10¹² Hz

C) 6.63×10¹ Hz

D) 1.6×10⁻¹⁰ Hz

Q: Which electromagnetic radiation has photons with the greatest momentum? (ET 2015)

A) Blue light

B) Yellow light

C) X-rays

D) Radio waves

Q: If 50 kV is the applied potential in an X-ray tube, the minimum wavelength of X-rays produced is (ET 2016)

A) 0.2 nm

B) 2 nm

C) 0.02 nm

D) 2 Å

Q: The energy of electron in the 15th orbit is (ET 2016)

A) -13.6×10⁻⁹ J

B) -3.4×10⁻⁸ J

C) 2.17×10⁻⁸ J

D) 1.5×10⁻⁷ J

Q: The energy of electron in excited state n=4 in Hydrogen atom is (ET 2010)

A) -13.6 eV

B) -3.4 eV

C) -0.85 eV

D) -1.5 eV

Q: Hydrogen atom absorbs energy and transitions from n=1 to n=4. Number of spectral lines observed (ET 2009)

A) 8

B) 4

C) 6

D) 10

Q: Which series of hydrogen spectrum lies in the ultraviolet region? (ET 2009)

A) Lyman

B) Balmer

C) Paschen

D) Pfund

Q: Region of spectrum used to determine structure of crystalline solids (ET 2011)

A) Visible

B) Infrared

C) X-rays

D) Ultraviolet

Q: If an atom exists in excited state n=5, maximum number of transitions is (ET 2011)

A) 6

B) 5

C) 10

D) 3

Q: Energy needed to ionize H-atom from its second excited state (ground state = 13.6 eV) (ET 2016)

A) 1.51 eV

B) 3.4 eV

C) 13.6 eV

D) 21.1 eV

Q: Electron drops from n≥3 to n=2. The spectral lines fall in which region? (ET 2015)

A) Visible

B) Ultraviolet

C) Infrared

D) None

Q: A laser beam can be sharply focused because it is (ET 2015)

A) Highly coherent

B) Intense

C) Plane polarized

D) Highly directional

Q: The shortest wavelength of radiation in Paschen series is (ET 2012)

A) RH/9

B) 9/RH

C) 9RH

D) 9+RH

Q: Lyman series lies in which part of the spectrum? (ET 2012)

A) Visible

B) Infrared

C) Ultraviolet

D) X-rays

Q: If an electron moves from n=1 to n=2, by how much does the radius increase? (Entry Test 2012)

A) 2 times

B) 3 times

C) 4 times

D) 5 times

Q: Rutherford's scattering experiment demonstrates (ET 2014)

A) Existence of X-rays

B) Existence of alpha particles

C) Mass-to-charge ratio of electron

D) Nuclear model of atom

Q: Which hydrogen spectral series lies in the visible region? (ET 2014)

A) Lyman

B) Paschen

C) Balmer

D) Pfund

Q: The half-life of radioactive source is 2.3 days. Its decay constant per day will be (Entry Test 2006)

A) 0.1

B) 0.2

C) 0.3

D) 2.3

Q: A neutron with K.E equal to 0.04 eV is called (ET 2016)

A) Slow neutron

B) Thermal neutron

C) Fast neutron

D) Both (a) and (b)

Q: Fast neutrons can be slowed down by collisions with (Entry Test 2007)

A) Electrons

B) Protons

C) Phonons

D) Photon