public goods and resources?

Question

Both public goods and common resources involve externalities.

(a) Are the externalities associated with public goods generally positive or negative? Is the free-market quantity of public goods generally greater or less than the efficient quantity? Use examples in your answer.
(b) Are the externalities associated with common resources generally positive or negative? Is the free-market use of common resources generally greater or less than the efficient quantity? Use examples in your answer.

Answer 1

a) positive--less than--knowledge
b negative--greater than--pollution

Answer 2

no they are a waste of time