71.

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

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