A physics student walks 100 meters in 80 seconds. The student stops for 30 seconds, and then walks 200 meters farther in 90 seconds. What is the average speed of the entire walk?
A. 0.67m/s
B. 1.5m/s
C. 1.8m/s
D. 3.5m/s

It really doesn't matter for any of the questions that you've listed.

The chemical reactions lab we did is typically called a "copper plating lab,  because the acid solution cleaned the pennies and made the copper look shinier;   the acid solution cleaned the paperclips and made them look like pennies;   &   the copper from the pennies was removed, and then added to the paperclips.