The ionisation energy of an electron in the ground state of a helium atom is $24.6 eV$. The energy required to remove both electrons is: (in $eV$)

Highly excited states for hydrogen-like atoms (also called Rydberg states) with nuclear charge $Ze$ are defined by their principal quantum number $n$,where $n \gg 1$. Which of the following statement$(s)$ is(are) true?
$(A)$ Relative change in the radii of two consecutive orbitals does not depend on $Z$
$(B)$ Relative change in the radii of two consecutive orbitals varies as $1/n$
$(C)$ Relative change in the energy of two consecutive orbitals varies as $1/n^3$
$(D)$ Relative change in the angular momenta of two consecutive orbitals varies as $1/n$

Given below are two statements:
Statement $I$: Atoms are electrically neutral as they contain equal number of positive and negative charges.
Statement $II$: Atoms of each element are stable and emit their characteristic spectrum.
In the light of the above statements,choose the most appropriate answer from the options given below.

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

The nature of the sun's spectrum is

$A$ neon sign does not produce