Need help solving few questions please!!

Q1 Suppose you have a 3.9 C charge and a 270 N/C electric field that points due east.

a)What is the magnitude of the force, in newtons, exerted on the charge by the electric field?

Q2 Suppose there is a 6.5 106 N/C electric field in some region.

a) Calculate the magnitude of the acceleration, in meters per second squared, of a proton from rest in such an electric field.

Q3 A charged particle (q = 7.5 10-10 C) experiences a force of F = 4.25i - 3.6j N in an electric field.

a) What would be an expression for the electric field vector E to which the charge is subject, in terms of the force F.

b) Assume this field is generated by a point charge of Q = 5 10-9 C. How far away is this charge located? Give your answer in meters.

Q4 Two charges are placed on the x axis, equidistant from the y axis. The first charge, q1=1.41C, is placed at the coordinates (d,0), and the second charge, q2=2.12C, is placed at the coordinates (d,0) where d=0.483m

a) There is a location on the x axis, (x0,0), where the net electric field has a magnitude of zero. What is the value, in meters, of x0?