Answer:
1. FALSE
There can still be gains from trade if one country has an Absolute advantage in the production of all goods because having absolute advantage does not mean that it has comparative advantage. If they did have comparative advantage in all goods then there would be no gain.
2. TRUE
As shown in the explanation above, gains from trade are determined by comparative advantage. If a country has comparative advantage in a good, it can gain from trading for a good it does not have comparative advantage in.
3. FALSE
Trade can and should be mutually beneficial to both countries.
4. TRUE
If both parties agree to a price that lies between their opportunity costs, they can make gains because they would be making more than their opportunity costs.
5. FALSE
The country has opened up to trade which means that the good they export now has a larger market to sell to. This will be beneficial to the people in the exporting industry as they will sell more and thus make more money.