The increasing order (lowest first) for the values of `e//m` (charge/mass) for electron `(e)`, proton `(p)`, neutron `(n)`, and alpha particle `(alpha)` is

Options

A. `e, p, n, alpha`
B. `n, p, e, alpha`
C. `n, p, alpha, e`
D. `n, alpha, p, e`

Answer

D

Explanation

Neutron has no charge, hence e/m is zero for neutron. Next, `alpha-` particle `(He^(2+))` has very high mass compared to proton and electron, therefore very small e/m ratio. Proton and electron have same charge (magnitude) but former is heavier, hence has smaller value of e/m. `(e)/(m), n lt alpha lt p lt e`