The Lyman series corresponds to the emission lines of hydrogen atom due to the transitions of the type $n \rightarrow 1(2 \rightarrow 1,3 \rightarrow 1,4 \rightarrow 1$, etc) where $n$ is the principal quantum number of the excited state. The ionization energy of the hydrogen atom can be determined by plotting:

• Correct answer
  A

  Frequency differences between successive emission lines vs emission frequencies
• B

  Emission frequency vs $n^2$
• C

  Emission frequency vs $1 / n^2$
• D

  Frequency differences between successive emission lines vs $n$

Hence, the correct answer is option: 'A'.