Pick out the correct statement from the following:

The spectrum obtained from a sodium vapour lamp is an example of

$A$ stationary hydrogen atom emits a photon corresponding to the first line of the Lyman series. The recoil velocity of the atom is nearly (in $m/s$)

Of the following pairs of species,which one will have the same electronic configuration for both members?

An electron of a stationary Hydrogen atom transitions from the fifth energy level to the ground level. The velocity that the atom acquires as a result of photon emission is ( $m=$ mass of the atom,$R=$ Rydberg's constant,$h=$ Planck's constant).

In the absorption spectrum of $Na$,the missing wavelength$(s)$ are: