With
7
9 and 8 but you don't have to do eight

7. Southern pacific ocean, southern atlantic ocean, southern ocean and caribbean sea.

8. The earths axis is tilted 23.5 o, that means that the seasons are different depending on the area, the north pole is pointing at the sun in july, where as the south is not.

9. Plains, mountains, oceans, lakes, woodlands, northwest plateau as well (they are both in that area.)

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.