Energy liberated in the de-excitation of hydrogen atom from the third level falls on a photo-cathode. Later when the same hoto-cathode is expoced to a spectrum of some unknown - like gas, excited to the second energy level , it is found that the de Broglie wavelength of the fastest photoelectrons now ejected has decreased by a factor of `3`. For this new gas, difference of energies of the second Lyman line and the first balmer line is found to be `3` times the ionization potential of the hydrogen atom. Select the correct statement (s):

Explanation

(a) z=2, (b) `phi =4.2 eV`