A copper sphere of mass `2.0 g` contains about `2xx10^(22)` atoms. The charge on the nucleus of each atom is `29 e (e= "electron charge")`. The mass of an electron is `9.11xx10^(-31) kg`. How much mass will the sphere lose or gain if it is given a charge of `+2 muC`?

Options

A. Loss a mass of `1.13xx10^(-14)g`
B. Gain a mass of `1.13xx10^(-14)g`
C. Neither gain nor lose any mass
D. Change in mass will depend upon the kinetic energy of the electrons

Answer

a

Explanation

To give position charge to the copper to the copper sphere, a certain number of free electrons must be removed.
The total number of electrons is `29(2xx10^(22))= 5.8xx10^(23)` Since a positive charge of `2 muC` is to be given the number of electrons to be removed
`(2xx10^(-6))/(1.6xx10^(-19))= 1.25xx10^(13)`
The mass of the electrons removed
`=1.25xx10^(13)xx0.91xx10^(-30)kg`
`= 1.13xx10^(-17)kg= 1.13xx10^(-14)kg`
This mass will be lost by the copper sphere.