Which of the following statements is true about the atoms of any element

The number of protons in an atom of an element is unique to each element. A proton in an atom of one element is identical to a proton in an atom of another element. The number of protons in an atom of an element is the same for all elements.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me