Question

The charge on alpha particle is
$
  (a){\text{ 1}}{\text{.6}} \times {\text{1}}{{\text{0}}^{ - 10}}C \\
  (b){\text{ 3}}{\text{.2}} \times {\text{1}}{{\text{0}}^{ - 19}}C \\
  (c){\text{ - 3}}{\text{.2}} \times {\text{1}}{{\text{0}}^{ - 19}}C \\
  (d){\text{ - 1}}{\text{.6}} \times {\text{1}}{{\text{0}}^{ - 19}}C \\
 $

Answer 1

Hint – In this question use the concept that alpha particles are positively charged, so option (c) and option (d) are directly eliminated in quest to find the right answer. In order to find the right answer, use that the charge on an alpha particle is twice the charge on a proton, but take magnitude of it.

Complete Step-by-Step solution:
As we know that the alpha particles are positively charged and it consists of two protons and two neutrons bound together in a particle (there is no electron on an alpha particle to balance the charge of proton).
So the electric charge on the alpha particle (q) = +2e.
Where e is the electronic charge whose value is equal to
$ \Rightarrow e = 1.6 \times {10^{ - 19}}$Coulombs.
So the charge on alpha particle is
$q = 2 \times \left( {1.6 \times {{10}^{ - 19}}} \right) = 3.2 \times {10^{ - 19}}$C.
So this is the required answer.
Hence option (B) is the correct answer.

Note – Alpha particles are identical to the nucleus of a helium atom. The rest mass of the alpha particle amounts to 4 a.m.u which equals to about $6.644 \times {10^{ - 27}}$ and its charge is +2e. An alpha particle is produced by the alpha decay of a radioactive nucleus. When the nucleus is unstable it ejects the instability causing the element to attain a more stable state.