Helpz me pleaz! I don't quite get it

What term is applied to a scientist who studies ancient life, including animal and plant fossils a. anthropologist b. dendroclimatologist c. geophysicist d. paleontologist

Before it was launched, a helium-filled balloon had a pressure of 201 kpa at a temperature of 27°c. at an altitude of 15,000 m, the pressure had decreased to 2.5 kpa and the temperature had dropped to -14 °c. the volume of the balloon increased to 59.3 m3. what is the original volume of the balloon? 13 m3 0.85 m3 0.077 m3 1.17 m3

Exit what is the density of an object having a mass of 5.0 g and a volume of 45.0 cm3?