Question

Hydrogen gas can only absorb EM radiation that has an energy corresponding to a transition in the atom, just as it can only emit these discrete energies. When a spectrum is taken of the solar corona, in which a broad range of EM wavelengths are passed through very hot hydrogen gas, the absorption spectrum shows all the features of the emission spectrum. But when such EM radiation passes through room-temperature hydrogen gas, only the Lyman series is absorbed. Explain the difference.

a) The solar corona contains only Lyman series transitions.

b) Room-temperature hydrogen selectively absorbs specific wavelengths.

c) Hot hydrogen gas emits a continuous spectrum.

d) The Lyman series is the only series present in the solar corona.

Answer 1

The absorption of EM radiation in hydrogen gas varies with temperature; room-temperature hydrogen mainly absorbs Lyman series due to most atoms being in the ground state, whereas very hot hydrogen in the solar corona can absorb multiple series due to a greater number of excited states.

Step-by-step explanation:

The difference in the absorption spectrum observed when electromagnetic (EM) radiation passes through hydrogen gas at different temperatures is due to the energy states of the hydrogen atoms. At room temperature, most hydrogen atoms are in their ground state, meaning they can only absorb photons corresponding to the Lyman series, which are transitions from the ground state to higher energy levels that occur in the ultraviolet region.

However, in very hot environments like the solar corona, the hydrogen atoms have more excited states due to the high temperature, allowing them to absorb photons of various wavelengths corresponding to multiple series, such as Lyman, Balmer, and others. Thus, when EM radiation passes through hydrogen gas in the solar corona, it can show all the features of the emission spectrum because the atoms are excited to various energy levels.