A paisa coin is made up Al-Mg alloy and weighs 0.75 g. It has a square shape and its diagonal 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 conclusion do you draw from this magnitude ?

Explanation

Here, given quatities are
Mass of a paisa coin =0.75g
Atomic mass of aluminium `=26.9815g`
Avogadro's number `=6.023xx10^(23)`
`therefore` Number of aluminium taoms in one paisa coin.
`N=(6.023xx10^(23))/(26.9815)xx0.75=1.6742xx10^(22)`
As charge number of Al is 13, each atom of Al contains 13 protons and 13 electrons
`therefore` Magntiude of positive and negative cahrges in one paisa coin`=Nze`
`=1.6742xx10^(22)xx13xx1.60xx10^(-19)C`
`=3.48xx10^(4)C=34.8kC`
This is a very large amount of charge. thus, we can conclude that ordinary neutral matter contains enormous amount of `+-` charges.