what is the process that best describes how the earth was sorted into different layers based on density

Ais useful when you need a simple machine to you separate two things. a. lever b. screw c. pulley d. wedge

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.

How many neutrons does element x if it’s atomic number is 28 and its mass number is 87