Why is stepping on a can considered a physical change?

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

Surface currents are caused by blank space . question 14 options: surface currents are caused by? differences in water temperature high salinity differences in density wind forces

Click the button that shows the correct relationship of the electron affinities of the elements sodium and phosphorus. sodium’s electron affinity value is more negative than the electron affinity value of phosphorus. phosphorus’ electron affinity value is more negative than the electron affinity value of sodium. this information cannot be determined using the periodic table. answer is b on e2020.