If the total energy of an electron in a hydrogen atom in an excited state is $-3.4 \ eV$,then the de-Broglie wavelength of the electron is

$A$ proton and a $Li^{3+}$ nucleus are accelerated by the same potential. If $\lambda_{Li}$ and $\lambda_{P}$ denote the de Broglie wavelengths of $Li^{3+}$ and proton respectively,then the value of $\frac{\lambda_{Li}}{\lambda_{P}}$ is $x \times 10^{-1}$. The value of $x$ is ............
(Rounded off to the nearest integer)
(Mass of $Li^{3+} = 8.3 \times \text{mass of proton}$)

What is the de-Broglie wavelength associated with the hydrogen electron in its third orbit?

What is the de Broglie wavelength of an electron in the $n^{th}$ Bohr orbit?

The de Broglie wavelength is given as $1 \, \mathring{A}$ and the value of $h$ is $6.6252 \times 10^{-27} \, \text{erg} \cdot \text{s}$. What will be the momentum of the particle (in $\text{g} \cdot \text{cm/s}$)?

Calculate the wavelength (in nanometer) associated with a proton moving at $1.0 \times 10^3 \ m \ s^{-1}$. (Mass of proton $= 1.67 \times 10^{-27} \ kg$ and $h = 6.63 \times 10^{-34} \ J \ s$)