Question

The order (lowest to highest) of e/m (charge/mass) ratio for electron (e), proton (p), neutron (n) and alpha particle $\left(\alpha \right)$ is:

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

Answer 1

The correct option is D $n,\alpha ,p,e$

	The increasing order (lowest to highest) of e/m (charge/mass) ratio is $n<\alpha <p<e$. Neutron being neutral has zero charges and lowest e/m ratio. An electron has a unit charge but negligible mass. Hence, the electron has a maximum e/m ratio. For an alpha particle, the e/m ratio is 2/4 or 0.5. For proton, e/m ratio is 1/1 or 1.