A uniform electric field exists in a region of space. Potential at potential O,A,B and C are

A uniform electric field exists in a region of space. Potential at potential O,A,B and C are `V_(0)=0` and `V_(A)=-1V,V_(B)=-6V` and `V_(C)=-3V` respectively. Alll the cubes shown in fig have side length of 1m. ltbr. (a). Find `V_(P)-V_(Q)` (b). Find the smallest distance of a point from O where the potential is `-2V`