How do you throw a pair of clipers

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

In a heat engine if 1000 j of heat enters the system and the piston does 500j of work, what is the final internal energy of the system if the inital energy was 2000 j1.write the equation2.list out your known variables 3. plug the numbers into the equations4.solve 5.write your solution statement that includes initial energy and final energy added.

State the below theories and give the name of the writer of the theory 1. wave theory 2. quantum theory 3. corpuscular theory 4. electromagnetic theory