Which statements about carbon-14 dating are true? Check all that apply. Carbon-14 decays into nitrogen-14. Carbon-14 has a longer half-life than potassium-40. Once a living thing dies, it no longer takes in carbon. Carbon-14 dating is used to date very old volcanic rock. Carbon-14 dating works for fossils as old as 50,000 years.

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.