How do u do this. i'm completely confused

When it flattens out that means there is a constant rate of hydrochloric added to the zink

I think the flat line is like a resting point in where there is nothing is being added or taken awaya example might be a graph shows how far you walked and there is a few flat sections to the graph it shows where you took restsall graphs i think are the same flat line segment shows a restin your case it is the pause in the hydrochloric acid being added

It feels feed the echo system

Of the cold they can survive in the cold