Given
:λelectron λparticle =1.8×10−4
and
velectron vparticle =3
According to de-Broglie equation,
λ=mvhλelectron λparticle =mparticle ×vparticle h×hmelectron ×velectron =mparticle melectron ×vparticle velectron ⇒1.8×10−4=mparticle 9.1×10−31kg×31mparticle =1.8×10−4×39.1×10−31=1.6852×10−27kgActualmassofneutronis1.67493 \times 10^{-27}
kg. Hence, the particle is neutron.