9. Equations for reactions of iron and iron compounds are shown. Fe + 2HCl → FeCl2 + H2
2FeCl2 + Cl2 → 2FeCl3
FeSO4 + Mg + Fe + MgSO4
FeSO4 + 2NaOH → Fe(OH)2 + Na2SO4
How many of these are redox reactions?
A 1
B 2
С 3
D 4

Which of the following is an example of how telecommunication devices people do their jobs? a.) a security guard checks the time using a digital watch. b.) a banker does some quick math using a solar calculator. c.) a nurse uses a digital thermometer to take a patient’s temperature. d.) a construction worker reports in to his office using a cell phone.