Two spheres of copper, having mass 1 g each, are kept 1 m apart. The number of electrons in them are 1 % less than the number of protons. The electrical force between them is Atomic wt. of copper is 63.54 g/mol, atomic number is 29, Avogadro's number `N_A = 6.023 xx 10^23 mol^(-1)` and `k = 9 xx 10^9` SI

Explanation

The number of electrons and protons are 29 each in neutral copper atom. The number of electrons are less than that of proton by 1%. i.e. In a charge in one atom is 0.29 e. (+ ve). The no. of atom in 1 g of copper
`=("Avogadro number")/("atomic wt.")`
`therefore n = (6.023 xx 10^(23))/(63.54)`
The positive charge in 1g of copper
`q = (6.023 xx 10^(23))/(63.54) xx 0.29e (therefore q= "ne")`
`therefore q = 439.8 C`
The force between two spheres.
`F = (kq^(2))/r^(2)`
`=(9 xx 10^(9) xx (439.8)^(2))/(1)^(2)`
`therefore F = 1.74 xx 10^(15)` N