The wavelength of the radiation emitted when in a H atom, the electron falls from infinity to stationary state (n=1), is:

1. $15$ $nm$

2. 192 nm

3. 406 nm

4. 91 nm

The energy and the radius of the first orbit of He⁺ are respectively :

1. $-8.72\times 10^{-18}J$; 0.02645 nm

2. $8.72\times 10^{-18}J$; 0.02645 nm

3. $-7.82\times 10^{-18}J$ ; 0.03655 nm

4. $7.82\times 10^{-18}J$; 0.03655 nm