Question

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

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

Answer 1

Answer: (D)

n, $\alpha,$ p, e

Answer 2

Neutron has no charge, hence e/ m is zero for neutron. Next, a-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 el m. $\frac{e}{m} ; n < \alpha < p < e$