For  $H{e}^{+}$ , a transition takes place from the orbit of radius 105.8 pm to the orbit of radius 26.45 pm.
The wavelength (in  $\stackrel{0}{A}$) of the emitted photon during the transition is  $x\times {10}^2$  then  $x$  
[Use : Bohr radius, a = 52.9 pm; Rydberg constant ,  $R_H=2.2\times {10}^{-18}J$  ; Planck’s constant , $h=6.6\times {10}^{-34}Js$  ; Speed of light , $c=3\times {10}^{8}m{s}^{-1}$ ]