Each element has its own emission and absorption lines. What is the best explanation for this? Each element has a specific number of protons and neutrons.
Each element has a distinct number of electrons.
Each element has a unique set of physical characteristics.
Each element has unique energy levels.

Apulley system is used to lift a 2,000 newton engine up a distance of 3 meters. the operator must apply a force of 250 newtons to the chain of the pulley system to lift the motor. to lift the engine 3 meters, the operator must pull a total of 30 meters of chain through the pulley system. what is the value of di?

One form of energy can be another type of energy. a. created to form b. transformed into c. destroyed and then created to form

The air that we breath is made mostly of which gaseous molecule