Illustrate: A question which asks you to illustrate usually requires you to explain or clarify your answer to the problem by presenting a figure, picture, diagram, or concrete example. This outline does not have to be detailed.
You'll need to give an overview of the literature. Distinguish — when they ask you to distinguish, it means you need to explain the differences between two or more items. Review these, and most of all note that there are different ways of answering a question or writing a paper! A definition of power from a physics text may not be what we want in our discipline.
Give an account of Means give a detailed description of something. Compare Identify the characteristics or qualities two or more things have in common but probably pointing out their differences as well.
Objective — bare information, expressing no emotions or personal opinions. To provide as much detail as possible, and to give definitions for any jargon or key terms when used.
Readability — an ease with which readers can understand your written text.