Atomic Structure 1 Question 35
11. 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
$(1984,1 \mathrm{M})$
(a) $e, p, n, \alpha$
(b) $n, p, e, \alpha$
(c) $n, p, \alpha, e$
(d) $n, \alpha, p, e$
Show Answer
Answer:
Correct Answer: 11. (c)
Solution:
- Neutron has no charge, hence $e / m$ is zero for neutron. Next, $\alpha$-particle $\left(\mathrm{He}^{2+}\right)$ 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 $e / m$.
$$ \frac{e}{m}: n<\alpha<p<e $$
