Question

The increasing order for the magnitude of $e/m$ (charge/mass) for an electron (e), a proton (p) and a neutron (n) respectively is:

• A. $e<p<n$
• B. $n<p<e$
• C. $n<e<p$
• D. $p<e<n$

Answer 1

The correct option is B $n<p<e$

An electron and a proton have the same magnitude of charge. A neutron has no charge.
Mass of electron is $\frac{1}{1840}$ times the mass of proton.
Hence the order of $e/m$ becomes: $n<p<e$.