just help me with 2a) but if you have a lot of time you can just give me answer for all of it so i can check my answer , thank you if u help me , i really nedd help

The reaction forming aluminum bromide is Al + 3Br2 → 2AlBr3

D. the number of organisms an ecosystem can support.

the  carrying capacity   of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment. thus, it is related to the maximum organisms that can be supported by the resources present in that ecosystem.