To solve this problem, we need to use the formula for the torque experienced by an electric dipole in an electric field.$\\$The torque $(\tau)$ experienced by a dipole is given by:$\\ \tau = pE \sin \theta \\$where:$\\$• $p$ is the dipole moment.$\\$• $E$ is the electric field intensity.$\\$• $\theta$ is the angle between the dipole and the electric field.$\\$Given:$\\$• $\tau = 4$ Nm$\\$• $E = 2 \times 10^5$ N/C$\\$• $\theta = 30^\circ \\$The dipole moment $(p)$ is also given by:$\\ p = q \cdot d \\$where:$\\$• $q$ is the charge on the dipole.$\\$• $d$ is the separation between the charges (dipole length).$\\$Given:$\\ d = 2$ cm$= 0.02$ m$\\$Substitute the known values into the torque formula:$\\ 4 = (q \cdot 0.02) \cdot (2 \times 10^5) \cdot \sin 30^\circ \\$Since $\sin 30^\circ = \frac{1}{2},$ we have:$\\ 4 = (q \cdot 0.02) \cdot (2 \times 10^5) \cdot \frac{1}{2} \\$Simplify:$\\ 4 = q \cdot 0.02 \cdot 10^5 \\ 4 = q \cdot 2000 \\$Solve for $q: \\ q = \frac{4}{2000} \\ q = 0.002$ C$\\$Convert the charge to milliCoulombs (mC):$\\ q = 0.002 \times 1000$ mC$\\ q = 2$ mC$\\$Therefore, the magnitude of the charge on the dipole is $2$ mC.$\\$This corresponds to Option 4.