Your answer is rounded to 3 but the specific is 3.6132849e+24
When a stable atom gains or loses its electrons then that’s when it becomes the ion.
Yes, it is. The pencil is still composed of wood and graphite before and after the break, although the physical form is different, of course. If you wanted a comparison, burning the pencil would be a chemical change.
Don’t have a calculator on me but multiply 6.02x10 to the 23rd power by 4.5