A common isotope of Carbon has an atomic number of 6 and a mass number of 13. How many neutrons are in an atom of this isotope? A. 6
B. 7
C. 12
D. 13

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.