In which orientation,a dipole placed in a uniform electric field is in (i) stable equilibrium (ii) unstable equilibrium?

(1)When the dipole is aligned parallel to the electric field (i.e. the angle between dipole moment and the electric field is $0^o$), then the dipole is in stable equilibrium.

(2)When the dipole is aligned anti-parallel to the electric field (i.e. the angle between dipole moment and the electric field is ${180}^o$), then the dipole is in unstable equilibrium.