What does an electric dipole experience when placed in a uniform electric field?

An electric dipole is placed in a uniform electric field $\vec{E}$ of magnitude $40\ N/C$. The graph shows the magnitude of the torque $\tau$ on the dipole versus the angle $\theta$ between the field $\vec{E}$ and the dipole moment $\vec{p}$. The magnitude of the dipole moment $\vec{p}$ is equal to:

When does the torque acting on an electric dipole in a uniform electric field become zero?

An electric dipole has a charge of magnitude $q$ and a dipole moment $p$. It is placed in a uniform electric field $E$. If its dipole moment is aligned with the direction of the electric field, the force acting on it and its potential energy will be, respectively:

An electric dipole of length $4 \ cm$ is placed with its axis making an angle of $30^{\circ}$ with a uniform electric field of $10^6 \ N/C$. If it experiences a torque of $20 \sqrt{3} \ Nm$,then the potential energy of the dipole is $:-$ (in $J$)

An electric dipole of moment $p$ is placed at the origin along the $x$-axis. The electric field at a point $P$,whose position vector makes an angle $\theta$ with the $x$-axis,will make an angle $\phi$ with the $x$-axis. If $\tan \alpha = \frac{1}{2} \tan \theta$,where $\alpha$ is the angle between the electric field vector and the position vector,then the angle $\phi$ that the electric field makes with the $x$-axis is: