It is for my macroeconomics class. Thanks

1 - Explain why scarcity leads to trade-offs. 2 - Name the three main categories of economic trade- offs. 3 - What are the three main components of interest rate? 4 Explain why is a production possibility frontier curved. (Hint: What underlying principle or law does it illustrate? What does it mean in terms of opportunity cost?) 5 What is a positive economic statement? Please give an example. 6 - Overall how can self-interest be a good thing for society? (Consider the aspect of an individual's education or firms developing innovative products.) Can self-interest help society? Please explain