Unit 2.10 - Paper 2 Exam Practice QuestionsDefine the term market failure. [2]Define the term positive externalities. [2]Describe why external costs are a source of market failure. [2]Explain why tobacco is an example of a demerit good. [2]Explain one disadvantage of implementing a per unit tax to eradicate negative externalities. [2]Answers1. Define the term market failure. [2]