Question

The increasing order of the values of $\dfrac{e}{m}$ (charge/mass) for electron (e), proton (p), neutron (n) and alpha particle ( $\alpha $ ) is:
(A) $e,p,n,\alpha $
(B) $n,p,e,\alpha $
(C) $n,p,\alpha ,e$
(D) $n,\alpha ,p,e$

Answer 1

Hint: Because of both charges of the electron and the mass of the electron are small, measuring both quantities of an electron is a different task. The ratio of the two fundamental constants can be determined easily and precisely from the radius of the electron in a known magnetic field.

Complete step by step solution:
The electron is a low mass with a negatively charged particle.
Mass of an electron (m) = $9.10938356X{{10}^{-31}}ki\log rams$
Charge of electron (e) = $1.602X{{10}^{-19}}coulombs$
Once the electron discovered by J.J.Thomson derived a formula for the charge to mass ratio of an electron.
The charge to mass ratio of electron is given by, $\dfrac{e}{m}=1.758820X{{10}^{-11}}C/Kg$
For neutron, there no charge for this article, so, the charge to mass ratio for neutron = 0
For alpha particle, the mass of an alpha particle with two positive charges = 2 X mass of proton + 2 X mass of a neutron
Approximately, the mass of an alpha particle is approximately equal to 4 times a proton.
Mass of proton with one positive charge, and mass of electron which is less than $\dfrac{1}{1837}amu$ times the mass of a proton.
For alpha particles, charge to mass ratio = $\dfrac{e}{2{{m}_{p}}}$
Where, ${{m}_{p}}=mass\text{ }of\text{ }proton$ , e= charge of electron
For proton, charge to mass ratio = $\dfrac{e}{{{m}_{p}}}$
For electron, charge to mass ratio = $\dfrac{e}{{{m}_{e}}}$
Where, ${{m}_{e}}=mass\text{ }of\text{ electron}$

The correct answer is option (D) - $n,\alpha ,p,e$.

Note: The particle which carries positive or negative charge is charged particles. Ions may be positively or negatively charged based on gain by electrons or loss of electrons in the outermost shell of the atom. The charge to mass ratio is also known as the specific charge of particles.