<p>Radiation given out during transition of n = 2 to n = 1 for H-atoms are allowed to fall on&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>H</mi><msup><mi>e</mi><mo>+</mo></msup></math>&nbsp;ions in n = 1 and n = 2 states. The possible transitions of helium ion due to absorption of energy is:</p>