What is the difference between Positive and Normative Economics?

Why the PPC is concave, based on opportunity costs and slope.

For a price floor to be binding, should it be above or below the equilibrium? What is an example of a binding price floor?

Which type of utility looks at utils and which type of utility looks at indifference curves?

What is the difference between accounting profits and economic profits?

Which effect dominates when the labor supply curve is backward bending: the substitution effect, or the income effect?

short answer questions. that I had trouble explaining