(i) On resolving the vectors `W = mg` and `F = qE`, we get `mg sin theta = qE cos theta (1)`
(at equilibrium position)
(ii) From (1)
`tan theta = (qE)/(mg)`
Substitute the values of `q,E,m` and g and obtain the angle subtended by the pendulum with the vertica.
(iii) `theta = tan^(-1) (0.75)`