If the potential energy of the electron is $-10 \ eV$,what is the total energy in $eV$?

If the velocity of an electron in the $n^{th}$ orbit of a Bohr atom is $v$,what is the value of $n$?

Bohr's radius can have

Henry Moseley studied the characteristic $X$-ray spectra of elements. The graph which represents his observation correctly is: (Given $\nu =$ frequency of $X$-ray emitted; $Z =$ atomic number)

$A$: Thomson's atomic model is known as the plum pudding model.
$R$: The atom is considered as a positively charged sphere in which electrons are embedded.

The ratio of the lowest energy in terms of wave numbers of the Balmer and Lyman series of lines of the atomic spectrum of hydrogen is