Question

The increasing order of a specific charge to mass ratio of electron$\left(e\right)$, proton$\left(p\right)$, alpha particle$\left(\alpha \right)$ and neutron$\left(n\right)$ is:

• A. $e,p,n,\alpha$
• B. $n,p,e,\alpha$
• C. $n,\alpha ,p,e$
• D. $n,p,\alpha ,e$

Answer 1

Answer: (C)

$n,\alpha ,p,e$

The value of charge divided by the mass of an atom or a subatomic particle is called a specific charge.

The charge of a neutron is zero. Hence, its specific charge is zero.

For $\alpha$:
$\frac{e}{m}=\frac{2\times 1.6022\times {10}^{-19}}{4\times 1.672\times {10}^{-27}}=4.8\times {10}^7$
For electron:
$\frac{e}{m}=\frac{1.6022\times {10}^{-19}}{9.109\times {10}^{-31}}=1.76\times {10}^{11}$
For proton:
$\frac{e}{m}=\frac{1.6022\times {10}^{-19}}{1.672\times {10}^{-27}}=9.58\times {10}^7$
$\therefore$ Order is $e>p>\alpha >n$

Option C is correct.