If domestic and foreign prices rise by the same relative amount, what will happen to the trade balance?

The above figure shows the market for fertilizer. When fertilizer is applied to lawns, it runs off into neighboring streams and ponds, killing fish and creating an external cost

a) What is the equilibrium price and quantity of fertilizer in an unregulated, competitive market? b) What is the efficient quantity of fertilizer? c) Suppose government imposes a tax equal to the marginal external cost. What is the equilibrium price paid by consumers and the equilibrium quantity after implementation of the tax? d) At the output level in part (c), how much is the tax? e) How much tax revenue does government collect? f) What is the deadweight loss borne by society if the externality is left uncorrected?

Industries with high barriers to entry

a. Pushes profits to normal returns b. increases the likelihood of firms entering the industry c. help firms sustain profits d. increases the number of competitors