Which of the following statements is true?
-weathering is a constructive forces which can build landforms.

-the crust beneath africa is thinner than the crust beneath the atlantic ocean.

-mold fossils form when dissolved minerals harden in the space once occupied by a dead organism.

-the amount of water which evaporates through the water cycle is greater than the amount which falls as precipitation.

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.