A particle is moving three times as fast as an electron. The ratio of the de Broglie wavelength of the particle to that of the electron is 1.813 × 10–4. Calculate the particle’s mass and identify the particle.
Broglie expression is given by
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m is the mass
h is he planks constant
v is velocity
is wavelength
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(4)/(1) => 
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of proton is ![]()
of neutron is ![]()
From the above the particle must be neutron.