Answer:
In water or acids, the metals trade places with hydrogen. The hydrogen escapes as a gas, and metal atoms, no longer attached to the object from which they came, dissolve in solution.
sorry if I'm wrong but I wrote this in my hw and it was right so ye
Gas exchange in humans is the delivery of oxygen lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs.
The answer is D because they speard apart or interact in all boundaries.