Answer:
Helium because it's apart of the noble gases family
Answer:
metals
Explanation:
Approximately three-quarters of all known chemical elements are metals. The most abundant varieties in the Earth's crust are aluminum,... Gold (Au), chemical element, a dense lustrous yellow precious metal of Group 11 (Ib), Period 6, of the periodic table.
6.21 x 10^3 = (Move decimal point 3 spaces to the right)
6210
6210 (0.1050)
652.05
Answer:
there are 6 significant figures in 107.051
Because usually when Ba forms ion it will form Ba2+. But when Fe forms ion, it can form Fe2+ or Fe3+. So you need to distinguish them by add their valence at the name.