Answer:
1mole of Argon contains 6.022x10^23atoms
3moles will contain
3x6.022x10^23atoms
1 atoms of Argon contains 18electrons
3x6.022x10^23atoms will contain...
3x6.022x10^23 x 18electrons
= 3.252x10^25electrons
Note:In a Neutral Argon... No of Electrons and Protons(positive charge) are the same
From Charge Quantization Principle
Q=ne
n=3.252x10^25protons
e=1.6x10^-19C
Q=3.252x10^25 x 1.6x10^-19
Q=5.2x10^6C
