A small smooth pulley is fixed at the highest point A of a cross-section ABC of a triangular prism. Angle \(\angle ABC = 90^\circ\) and angle \(\angle BCA = 30^\circ\). The prism is fixed with the face containing BC in contact with a horizontal surface. Particles P and Q are attached to opposite ends of a light inextensible string, which passes over the pulley. The particles are in equilibrium with P hanging vertically below the pulley and Q in contact with AC. The resultant force exerted on the pulley by the string is \(3\sqrt{3} \text{ N}\) (see diagram).

(i) Show that the tension in the string is 3 N.

The coefficient of friction between Q and the prism is 0.75.

(ii) Given that Q is in limiting equilibrium and on the point of moving upwards, find its mass.