What does the ricardian theory state? countries should produce all goods and services if they can countries should not produce goods and services that minimize opportunity costs countries should import goods and services if they are cheaper in other countries countries should export all goods and services if they make a profit

I believe the second to last one is correct and its Richardian not Ricardian. okay so Richardian Theory onh international trade is basicaly like this. lets say country A produces product X and specializes in producing product Y and country B also produces product Y but specializes in producing product X. so these countries would trade because one country needs the other product and so forth. erm i dunno if this helps

What was the length to begin with?

Ifound the exercise on the internet. attached is the list mentioned above.in order for a compound to be considered optically active it can't have any axis or plan of symmetry. the molecule  shouldn't also  be superimposable on its mirror image.with such considerations, the compounds that are optically active are: -third compound on the first image is optically active; -second and third compound from the second image are optically actives.