in a Millikan's oil drop experiment the charge on an oil drop is calculated to be 6.35 x 10 19C the number of excess electrons on the drop is

Explanation

We can find the number of excess electrons on the oil drop using the following steps:Define the charge of an electron:The charge of a single electron is a fundamental constant, approximately equal to:e = 1.602177 x 10^-19 CCalculate the number of electrons:Divide the total charge on the oil drop by the charge of a single electron:Number of electrons = Charge on oil drop / Charge of an electronNumber of electrons = 6.35 x 10^-19 C / 1.602177 x 10^-19 C/electronRound the result:Since we're dealing with a very small number, it's customary to round the result to a reasonable number of significant figures. In this case, 1 significant figure is appropriate:Number of electrons ≈ 4