(1) I observe that the number of plants decreases strictly as lead concentration increases.
(2) Feed this into Wolfram Alpha:
{(0, 48),(20, 45),(40, 40),(60, 34),(80, 23),(100, 13),(120, 7),(140, 2),(160, 1),(180, 0)}
Results attached. A scatter plot is adequate.
(3) The graph is easier to interpret, and more details of the pattern are apparent. The curve is not a straight line. I would add that at lower concentrations, adding 20mg lead per kg soil leads to a somewhat slower decrease in number of plants, with the fastest decrease coming around 60 to 100 mg per kg. At 140, most of the plants are absent.
