A neutral point is obtained at the centre of a vertical circular coil carrying current. The angle between the plane of the coil and the magnetic  meridian is

Magnetic meridian is a vertical N-S plane, the earth's magnetic field (BH) lies in it. .To obtain neutral point at the centre of coil, magnetic field due to current (B) and BH must cancel each other. Hence, plane of the coil and magnetic meridian must be perpendicular to each other as shown