How long would it take a sample of C-14 to undergo 2 half-lives?

Write a paragraph that provides examples of each stage of volcanic activity, a description of the volcano, and facts about each stage.

The peak wavelength for the blackbody curve of a star is in the uv range. assuming the radiation from this star can reach earth, would you be able to see it?

A50.0g sample of liquid water at 0.0 c ends up as ice at -20.0 c. how much energy is involved in this change?