Erosion
waethring
deposition
pressure or heat
all of this can change the form of rock to another
The answer to that is mass and chemical
Octet means presence of a total of 8 electrons in its valence shell while in case of duplet only 2 electrons are present in valence shell.
The tendency of iron to rust depend on the Ph of solution
The formation of rust increases as the PH decreases. This led agent of rusting that is oxygen gets more positive as H+ ions increase which facilitate rusting. The lower the Ph level the quick the corrosion.
They have 6 valance electrons.