You kind of need to show more, but the independent variable would be something that you are changing to then measure the reaction, like the time left in for example.
The radioactive isotope's atomic number decreases by two, and the alpha particle has an atomic number of 2. It wasnt clear which one you were asking for, so there is both.
The sort of adaptations that are usually passed to the offspring of an organism is the adaptation that helps it survive in its environment.
