Consider the following sequence of reactions. \[ \mathrm{C}_6\mathrm{H}_5\mathrm{COONa} \xrightarrow{\text{NaOH/CaO}, \Delta} \text{X} \xrightarrow{\text{CO} + \text{HCl}, \text{Anhyd. AlCl}_3} \text{Y} \xrightarrow{\text{NaOH}} \text{A} + \text{B} \] If A is the reduction product of Y, what is B?
Which of the following represents the wavelength of spectral line of Balmer series of He$^+$ ion? (R = Rydberg constant, n $>$ 2)