Which issue associated with nuclear power is the biggest source of debate?

Which of the following pairs of elements belong to the same groupa. h and he b. li and bec. c and pb d. ga and ge

Silver tarnishes as silver metal reacts with hydrogen sulfide, h2s, in the air. in this reaction, dark silver sulfide, au2s, covers the surface of silver. when silver is polished, this coating of silver sulfide can be removed from the surface. this makes the silver shiny again. enter the coefficients that balance the tarnishing reaction equation. (type 1 for no coefficient.)

What is the percent by mass of oxygen in fe2o3