A sample of Co-60 has a mass of 20.0 grams initially. Given that the half-life for this radioisotope is 5 years, how many grams of the sample will still be Co-60 after four half-lives?

distance, luminosity, brightness, radius, chemical composition, and temperature

it takes on an electronical energy

it is a solid

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.