Question

The increasing order of specific charge of electron (e), proton (p), alpha particle \[\left( {{\alpha }} \right)\] and neutron (n) is:
A.e, p, n, \[{{\alpha }}\]
B.n, p, e, \[{{\alpha }}\]
C.n, \[{{\alpha }}\], p, e
D.n, p, \[{{\alpha }}\], e

Answer 1

Hint: The specific charge is given as the ratio of the charge of the particle to that of the mass of the particle. The SI unit of charge is expressed in Coulomb which is given as \[\left( {\text{C}} \right)\].

Complete step-by-step answer:
We know that,
\[{\text{specific}}\,{\text{change}} = \dfrac{{{\text{charge}}}}{{{\text{mass}}}}\]
We know that for neutron, \[\dfrac{{\text{e}}}{{\text{m}}} = 0\]
For \[{{\alpha }}\] particle, \[\dfrac{{\text{e}}}{{\text{m}}}\left( {{\text{H}}{{\text{e}}^{ + 2}}} \right)\], the mass is much higher than that of the electron and proton, so the ratio is a small value.
For, electron, \[\dfrac{{\text{e}}}{{\text{m}}}\] has a negative value. But it is higher than that of protons. It is because, mass of the proton is greater than the mass of the electron.
Therefore, the increasing order of specific charge is \[{\text{n}}\,{\text{ < }}\,{{\alpha }}\,{\text{ < }}\,{\text{p}}\,{\text{ < }}\,{\text{e}}\].

Additional information:
Atomic structure refers to the structure of an atom that consists of a nucleus in which the protons which are positively charged and neutrons exist. The negatively charged particles are called the electrons and it revolves around the center of the nucleus.
The postulates of Dalton’s Atomic theory are as follows:
1) Every matter is composed of atoms.
2) Atoms are not visible.
3) Elements contain only one type of atom in them.
4) Each atom has their own constant mass. The mass varies from element to element.
4) During a chemical reaction, atoms undergo various rearrangement.
5)Atoms can neither be created nor be destroyed but can be transformed from one form to another.
Demerits of this theory are:
1)The theory was unable to explain the existence of isotopes.
2)Nothing about the structure of the atom was appropriately explained.
3)Later, the scientists discovered particles inside the atom that proved, the atoms are divisible.

Hence, C is the correct option.

Note: The mass of a proton is approximately \[1.672 \times {10^{ - 24}}\]. The mass of a neutron is almost the same as that of a proton \[1.674 \times {10^{ - 24}}\]. The mass of the electron is approximately \[9.1 \times {10^{ - 31}}\].