Answer:
isotopes, there elements with a diffrent type atomic weight then the original, usally due to a higher amout of neutrons than the original. Some Isotopes are just as useable as the normal versions, but in some cases, such as Uranium, they can be even more radioactive than the original form
A wave.
Scientists now recognize that light can behave as both a particle and a wave.
Magnesium(?)
<span>2 HCl + Mg ? MgCl2 + H2</span>
