A paisa coin is made up Al.Mg alloy and weighs 0.75 g. It has a square shape and its diognal measures 17mm. It is electrically neutral and constants equal amounts of positive and negative charges . Treating the paisa coin made up of only Al, find the magnitude of equal number of positive and negative charges. What concluision do you draw from this magnitude ?

Explanation

Here, mass of a paisa coin `= 0.75g`
Atomic mass of aluminium `= 26.9815 gram`
Avogadro's number `= 6.023xx10^(23)`
`:.` Number of aluminium atoms in one paisa coin `N = (6.023xx10^(23))/(26.9815) xx0.75 = 1.6742xx10^(22)`
As charge number of A1 is 13, each atom of A1 contains 13 protons and 13 electrons.
`:.` Magnitude of positive and negative charges in one paissa coin = N Z e
`= 1.6742xx10^(22)xx13xx1.60xx10^(-19) C = 3.48xx10^(4) C = 34.8 KC`