The ionisation energy of an electron in the ground state of helium atom is 24.6 eV. The energy required to remove both the electron is
Options
(a) 51.8 eV (b) 79 eV (c) […]
Light emitted during the de excitation of electron from n=3 to n=2, when incident on a metal, photoelectrons are just emitted from that metal. In which of the following de excitations photoelectric effect is not […]
The ratio of speed of an electron in ground state in Bohr’s first orbit of hydrogen atom to velocity of light in air (c ) is
Options
(a) e²/2ε₀hc (b) 2e²ε₀/hc (c) e³/2ε₀hc (d) […]
The Kα X-ray of molybdenum has a wavelength of 71×10⁻¹² m. If the energy of a molybdenum atom with K- electron removed is 23.32 keV, then the energy of molybdenum atom when an L-electron removed […]
The control rods used in a nuclear reactor can be made up of
Options
(a) graphite (b) cadmium (c) uranium (d) barium
Correct Answer:
cadmium
Explanation:
No explanation available. Be the first to […]
In Moseley’s law √ν=a(z-b), the values of the screening constant for K-series and L-series of X-rays are respectively
Options
(a) 1,6.4 (b) 1,4 (c) 4,6 (d) 2,4
Correct Answer:
1,6.4
Explanation:
No explanation […]
The wavelength of light emitted from second orbit to first orbit in a hydrogen atom is
Options
(a) 1.215×10⁻⁷ m (b) 1.215×10⁻⁵ m (c) 1.215×10⁻⁴ m (d) 1.215×10⁻³ m
Correct Answer:
1.215×10⁻⁷ m
Explanation: […]
The sodium nucleus ₁₁Na²³ contains
Options
(a) 11 electrons (b) 12 protons (c) 23 protons (d) 12 neutrons
Correct Answer:
12 neutrons
Explanation:
No explanation available. Be the first to write the explanation […]
The Rutherford scattering experiment proves that an atom consists of
Options
(a) a sphere of positive charge in which electrons are embedded like seeds of water-melon (b) a sphere of negative charge in […]
If, an electron in hydrogen atom jumps from an orbit of level n=3 to an orbit of level n=2, emitted radiation has a frequency (R=Rydberg’s constant, c=velocity of light)
Options
(a) 3Rϲ/27 (b) […]
2017 Copyright Doctor Dreams Training Academy