Potential and field at two electric plates

[kirby2]

fdsfds sdfs

 

[Delphi51]

Yes on both A and C. My explanation for A would be that work needs to be done to push a positive test charge from B to A against the force of the electric field. Your V=kq/r is obscure (unrelated to this question) because it is the absolute potential or work/charge for moving a charge from infinite distance into a position that is distance r away from charge q. It does tell you that the potential midway between the positive and negative plates is zero, though.

 

[kirby2]

and the other answers are wrong, correct?

 

[Delphi51]

Correct.