In hydrogen atom, electron excites from ground state to higher energy state and its orbital velocityis reduced to $\frac{1}{3}$rd of its initial value. The radius of the orbit in the ground state is R. The radius of the orbit in that higher energy

• 9 R

• 2 R

• 3 R

• 27 R

The most stable particle in the Baryon group is

• sigma particle

• neutron

• proton

• lambda particle

The ratio of the magnetic dipole moment to the angular momentum of the electron in the 1st orbit of hydrogen atom is

• $\frac{\mathrm{m}}{\mathrm{e}}$

• $\frac{\mathrm{e}}{2\mathrm{m}}$

• $\frac{\mathrm{e}}{\mathrm{m}}$

• $\frac{2\mathrm{m}}{\mathrm{e}}$

If n is the orbit number of the electron in a hydrogen atom, the correct statement among the following is

• electron energy varies as n²

• electron energy increases as n increases

• hydrogen emits infrared rays for the electron transition from n = ∞ to n = 1

• electron energy is zero for n = 1

In a Ruby laser, the colour of laser light is due to ........ atom

• chromium

• oxygen

• aluminium

• xenon

The additional energy that should be given to an electron to reduce its de-Broglie wavelength from 1 nm to 0.5 nm is

• 2 times the intial kinetic energy

• 3 times the initial kinetic energy

• 0.5 times the initial kinetic energy

• 4 times the initial kinetic energy

77.

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

• 51.8 eV

• 79 eV

• 38.2 eV

• 49.2 eV

Which of the following is not made by quarks ? 

• Neutron

• Positron

• Proton

• $\mathrm{\pi }$-meson

What is the de-Broglie wavelength of the electron accelerated through a potential difference of 100 V ?

• $12.27 \stackrel{\circ }{\mathrm{A}}$

• $1.227 \stackrel{\circ }{\mathrm{A}}$

• $0.1227 \stackrel{\circ }{\mathrm{A}}$

• $0.001227 \stackrel{\circ }{\mathrm{A}}$

Which of the following spectral series of hydrogen atom is lying in visible range of electromagnetic wave ?

• Paschen series

• Pfund series

• Lymen series

• Balmer series