The answer to the question "When a part rusts is becomes heavier or lighter?" is the rust actually has a tendency to flake off. But as long as the rust is still on the nail, the nail will be heavier. The reason is that you are actually adding an oxygen and hydrogen to the nail.
Carbon Dioxide (CO2) because it is essential to cellular processes that allow plants to thrive and generate oxygen that we can breathe. Nitrogen could also be an example of one gas that's important.
Answer:
In order to maintain the ability to reproduce, also to preform mitosis
<span>Igneous my dude, does lava things and stuff
:)</span>
