Atomic Spectra

The ratio of the kinetic energy and the total energy of the electron in the hydrogen atom, according to Bohr’s theory, is

• 1: - 1

• 1:1

• 1:2

• 1: - 2

Lyman series lies in ………….. region of hydrogen spectrum

• Ultraviolet

• Infrared

• Visible

• None of these

A Balmer line is emitted when the electron in a Hydrogen atom jumps from

• A higher orbit to the first orbit

• The first orbit to a higher orbit

• The second orbit to a higher orbit

• A higher orbit to the second orbit

The longest wavelength of the Lyman series is approximately

• 1420 A⁰

• 920 A⁰

• 1020 A⁰

• 1220 A⁰

If the electron in a Hydrogen atom jumps from the third orbit to the second orbit, the emitted radiation has wavelength (R is the Rydberg’s constant)

• 5R/6

• 6/5R

• 36/5R

• 5R/36

When objects placed in a room are exposed to X- rays, they appear

• Red

• Yellow

• Blue

• Invisible

When an electron jumps from higher orbit to lower orbit it emits photons of energy equal to:

• Difference of the energies in the two orbits

• Sum of the energies in the two orbits

• The energy of the higher orbit

• None of these

The transitions of inner shell electrons in heavy atoms give rise to the emission of:

• γ –rays

• x – rays

• β – rays

• None of these

The energy in electron volt needed to remove the most loosely bound electron from the natural atom is:

• Excitation potential

• Ionization energy

• Threshold energy

• Potential energy

Meta stable states have life time of the order of:

• 10^–8 sec

• 10^–6 sec

• 10^–3 sec

• 10^–10 sec