We know the formula for energy calculation is,

So, as the makes first transition,so n=1 and m=2.Thus we will obtain 2 energies at state 1 and state 2.The difference of the 2 energies will give us the excitation potential.

A.

Thus,

Therefore, the excitation energy of is,

B. Ionisation potential is defined as the energy required to ionise an atom(i.e.to remove one or more electron from the valence shell).The ionisation potential of hydrogen is 13.6eV.Thus,for any other atom it will be 13.6×

Thus, for ,we have atomic number,Z=3.

So ionisation potential =13.6×9=122.4 V