A.
Explanation:
Pioneer plants are to plants species that appear first in virgin land – such an after a volcanic eruption. They are mainly lower plants such as lichen, fungi, and noses. These species can grow on rocks and break them down over time to form soil. This is due to the fact that the plants have very shallow roots that can even grow in the small crevices of rocks and can draw water from the atmosphere – moisture. This releases the nutrients in the rocks and makes them available to higher plants that have deeper roots. The ecology of the region will ultimately be succeeded by a climax community over time, mainly dominated by tree species.
Answer:
The concentration is 
Explanation:
From the question we are told that
The absorbance is 
The length is 
Generally absorbance is mathematically represented as

where
is the molar absorptivity of FeSCN2 with a value 
and
is the equilibrium concentration of FeSCN2
So

substituting values

