How is the Mercalli scale formumated?

Why does physical weathering speed up the processes of chemical weathering? a) physical weathering requires abundant water, as does chemical weathering. b) physical weathering produces fresh surfaces for chemical weathering to attack. c) chemical weathering can occur only on small surfaces, not large ones. d) chemical weathering requires salt, which is provided by salt wedging.

What two advantages do the coastal countries of west africa have over the sahel countriesfertile soil and mineral resources temperatures and terrain human resources and natural resources weather patterns and location

What are the answers for the following questions?