Question

Which one of the following will have the maximum charge/mass ratio?

• A. Electron
• B. Proton
• C. Neutron
• D. Alpha particle.

Answer 1

The correct option is A

Electron

Explanation for correct option:

Option A: Electron:

Mass of electron$=\frac{1}{1867}\mathrm{u}$

Charge on electron$=\mathrm{e}$

Thus,

Charge to mass ratio of electron is$=\frac{\mathrm{e}}{{\displaystyle \raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$1867$}\right.}}=1867\mathrm{e}$

Thus, electron has the highest charge to mass ratio.

Explanation for incorrect option:

Option B: Proton:

Mass of proton$=1\mathrm{u}$

Charge on proton$=\mathrm{e}$

Thus,

Charge to mass ratio of proton is$=\frac{\mathrm{e}}{{\displaystyle 1}}=\mathrm{e}$

The charge to mass ratio of proton is less than that of electron.

Option C: Neutron:

Mass of neutron$=1\mathrm{u}$

Charge on neutron$=0$

Thus,

Charge to mass ratio of neutron is$=\frac{0}{{\displaystyle 1}}=0$

The charge to mass ratio of neutron is less than that of electron.

Option D: Alpha particle:

Mass of alpha particle$=4\mathrm{u}$

Charge on alpha particle$=2\mathrm{e}$

Thus,

Charge to mass ratio of alpha particle is$=\frac{2\mathrm{e}}{{\displaystyle 4}}=\frac{\mathrm{e}}{2}$

The charge to mass ratio of alpha particle is less than that of electron.

Thus, Option (A) is the correct option.