The charge on an electron is 1.6×10^-19C. How can I find the number of electron that flows per second to constitute a current of 2A?

Current refers to the charge that passes through a conductor during a given time period.

According to this definition, the current formula is:

Q/t = I

I = 2 A, t = 1 sec

Therefore,

Q = I*t

Q = 2*1 =2 C

An electon is composed of a charge of 1.6*10-19 C. This would then give rise to the number of electrons that are passing:

Q = n*e

Q/e = n

n = 2(1.6*10-19), = 1.25*1019 electrons