Answer:
n = 756.25 giga electrons
Step-by-step explanation:
It is given that,
If the charge on the negative plate of the capacitor,

Let n is the number of excess electrons are on that plate. Using the quantization of charges, the total charge on the negative plate is given by :

e is the charge on electron

or
n = 756.25 giga electrons
So, there are 756.25 giga electrons are on the plate. Hence, this is the required solution.