• Torque on an electric dipole $\vec{p}$ in an electric field $\vec{E}$ is:
  $$\vec{\tau} = \vec{p} \times \vec{E} \implies \tau = p E \sin\theta$$
  Since the dipole moment is parallel to the field, $\theta = 0^\circ$, hence $\sin 0^\circ = 0 \implies \tau = 0$.
• Net force on the dipole in a non-uniform field:
  Because the electric field is non-uniform, the magnitude of the field at the $+q$ charge differs from that at the $-q$ charge ($E_+ \neq E_-$). The forces $q\vec{E}_+$ and $-q\vec{E}_-$ do not cancel, resulting in a net non-zero translational force:
  $$F = p \frac{\partial E}{\partial x} \neq 0$$

Analysis of statements:

• Statement A is correct: By the law of conservation of charge, the net charge of an isolated system remains constant.
• Statement B is incorrect: In a conductor, excess charge redistributes over the outer surface to minimize electrostatic potential energy.
• Statement C is correct: $q = ne \implies n = \frac{1}{1.6 \times 10^{-19}} = 6.25 \times 10^{18}$ electrons.
• Statement D is incorrect: Electric field is a vector field (it has both magnitude and direction).
• Statement E is correct: A permanent dipole has a permanent intrinsic electric dipole moment even in the absence of an external electric field (e.g., water molecules).