Question

The first few electron energy levels within a single-electron atom are shown in above figure. Find out the energy of a photon that could NOT be emitted by this atom during an electron transition?

• A. $17eV$
• B. $42eV$
• C. $64eV$
• D. $255eV$
• E. $302eV$

Answer 1

The correct option is B $42eV$

Photon of a particular energy is emitted when electron makes transition from an energy level to other with energy difference equal to photon's energy.

The following energies are possible for given transitions,

$17ev$ for $4\to 3$

$64ev$ for $4\to 2$

$255ev$ for $2\to 1$

$302ev$ for $3\to 1$

we don't have any two energy levels having a difference of 42eV.