21. The number of grams of sulfur containing the same number of atoms as 5.00 moles of oxygen atoms is _.

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.

c

explanation: