principal factors

(a) Write a design of resolution Ill in seven factors and eight runs
(b) From {a) obtain a design in eight factors in 16 runs of resolution IV arranged in two blocks of 8.
(c) How could this design be used to eliminate time trends?
(d) What are the generators of the 16-run design?·
(e) If no blocking is used, how can this design be employed to study three principal factors, the main effects of eight minor factors not expected to interact with the major factors or with each other?