How many possible Mole Ratios are in the following reaction:
2 HgO --> 2 Hg + O2

In which layer of earth do most earthauakes occur a_ inner core b_outer core c_mantle d_crust

Element before carbon on the periodic table

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.