If electron, deutron, $\alpha$-particle and proton have same kinetic energy, which one has the largest de-Broglie wavelength.

electron

The correct answer is Option (3) → electron

According to De-Broglie

$λ=\frac{h}{P}=\frac{h}{\sqrt{2mKE}}$

$∴λ∝\frac{1}{\sqrt{m}}$

Mass: Electron < Deutron < α-particle

Velocity: Electron > Deutron > α-particle