Question

Arrange the electron(e) , proton(p), and deuteron(d) in increasing order of their specific charge-
A) \[\text{e > p < d}\]
B) \[\text{d < p < e}\]
C) \[\text{p > e > d}\]
D) \[\text{d > e > p}\]

Answer 1

Hint: Specific charge is defined as the charge per unit mass. The magnitude of charge is same for all the three particles i.e. electron, proton and deuteron whereas the mass is in the order of ${m_e} < {m_p} < {m_d}$ where ${m_e},{m_p}$ and ${m_d}$ are the masses of electron, proton and deuteron respectively.

Complete step by step answer:
The specific charge of a particle is defined as the charge per unit mass of the particle. All the given three-particles i.e. electron, proton, and deuteron carry the same magnitude of charge.
Electrons are the lightest particle and a deuteron is composed of an electron and in its nucleus there is a proton and neutron, therefore the deuteron is heaviest among the three given particles. Hence the order of masses is- ${m_e} < {m_p} < {m_d}$ where ${m_e}, {m_p}$ and ${m_d}$ are the masses of electron, proton and deuteron respectively.
As we see the specific heat is inversely proportional to mass, we can say the order of specific charge is-
$\text{Deuteron}$<$\text{proton}$<$\text{electron}$

$\therefore$ The increasing order of their specific charge is \[\text{d < p < e}\]. Hence option (B) is the correct answer.

Note:
The deuteron is an isotope of hydrogen, also called deuterium. Elements having the same atomic number but different mass numbers are called isotopes. Hydrogen has three isotopes i.e. protium, deuterium, and tritium having mass numbers 1, 2, and 3 respectively.