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

State whether the following statements are true or false:
$(i)$ When an electron in a hydrogen atom returns from the third excited state to the ground state,it emits frequencies corresponding to lines in the Lyman,Balmer,and Paschen series.
$(ii)$ When an electron in a hydrogen atom returns from the third excited state to the ground state,it emits radiation with wavelengths corresponding to the Pfund series,which has very high frequencies.

What is the approximate angular momentum (in $J \ s$) of an electron in a hydrogen atom in its ground state? $(h = 6.625 \times 10^{-34} \ J \ s)$

In a hydrogen atom, an electron is transferred from an orbit of radius $1.3225 \ nm$ to another orbit of radius $0.2116 \ nm$. What is the energy (in $J$) of the emitted radiation?

Based on the equation $E = -2.178 \times 10^{-18} \ J \left( \frac{Z^2}{n^2} \right)$,certain conclusions are written. Which of them is not correct?

Calculate the radius of the first orbit of $Li^{2+}$. (in $pm$)