Help me with this project, thanks

Question-1 The Canadian government won a big court decision. The Supreme Court said that carbon taxes were legal. Assuming that the federal government does make a tax on carbon dioxide, tell me what will happen. Be sure to use the terms of supply and demand.

Question-2 What problems might we foresee from the Bank of Canada's use of monetary policy to fight the COVID recession?

Question-3 What is a positive externality? How can they be encouraged?

please cite and provide full references