Question

How many coulombs of charge enter a 1.00 cm length of the axon during this process?

Answer 1

Let me explain the process and then you do the maths:
First: Find the number of ions crossing the lenght like this
5.6 x10^11 x 1 x10^-2
The resul of that you use it for quantization of charge crossing like this:
Previous result x 1.6 x10^-19
The result will give you the amount of coulombs you need