How do I find the answer for this question

Determine the number o moles of ions/atoms/particle in the following: 2.50 miles of k2s (let me know how to do)

Can someone me with questions 15 to 17 plz.

Which statement is usually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.