If all the assumptions about a perfectly competitive market or true, then at the equilibrium, what is true about the consumer and producer surplus?What are the major barriers to entry that explain the...

If all the assumptions about a perfectly competitive market or true,

then at the equilibrium, what is true about the consumer and producer surplus?What are the major barriers to entry that explain the existence of monopoly?What is the relationship between economies of scale and a natural monopoly? How does monopoly compare with perfect competition in terms of price, output, and efficiency?Perfect competition or monopoly industries will tend to be one-price industries. Monopolistic competition, however, is a multiprice industry". Explain.What are types of firms that exemplify monopolistic competition?What are the basic characteristics of oligopoly? How does oligopoly compare with the other market structures?