electric dipole consisting of charges of magnitude $1\mathrm{.}00nC$ separated by $6\mathrm{.}50m$ is in an electric field of strength $1300\frac{N}{C}.$

$($a$)$ What is the magnitude of the electric dipole moment?

C$.m$

$($b$)$ What is the difference between potential energies for dipole orientations parallel to and antiparallel to vec$(B)?$

J

Do you realize that the dipole moment magnitude equals the product of separation distance and the charge magnitude at either end? $($Don$\text{'}$t use the charge twice.$)$ Do you realize that "antiparallel" means opposite? Did you plug into the potential energy equation?