The de-Broglie wavelength $(\lambda)$ for electron $(e)$,proton $(p)$ and $He^{2+}$ ion $(\alpha)$ are in the following order. (Speed of $e$,$p$ and $\alpha$ are the same)

The frequency of the de-Broglie wave of an electron in Bohr's first orbit of a hydrogen atom is . . . . . . . . . . $\times 10^{13} \ Hz$ (nearest integer).
[Given: $R_H$ (Rydberg constant) $= 2.18 \times 10^{-18} \ J$,$h$ (Planck's constant) $= 6.6 \times 10^{-34} \ J \cdot s$]

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 $h = 6.63 \times 10^{-34} \ J \ s$)

If the kinetic energy of a particle is reduced to half,the de-Broglie wavelength becomes

Which is the correct relationship between wavelength and momentum of particles?

Which of the following has the lowest de Broglie wavelength $\lambda$?