What would you use if you needed to determine the density of an object?

balance and graduated cylinder
balance and scale
scale and spectroscope

If a sample of radioactive isotopes takes 600 minutes to decay from 400 grams to 50 grams, what is the half-life of the isotope?

Need , hurry pls create a superhero out of the element iron, what are its powers and his sidekick ( an element that works well with iron). how was the superhero made and who discovered him

The earth's surface is (science) a: studied using seismic waves b: constantly changing over time c: only studied indirectly d: the same today as million of years