Why does a pipe gain mass when it rusts?

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1 point
Matter is created during the chemical reaction.
Oxygen from the atmosphere bonded with the pipe to add mass to the pipe.
It does not gain mass because matter cannot be created.
Because it is going through a physical change.

3 answers

It does not gain mass because matter cannot be created.
wrong
Oxygen from the atmosphere bonded with the pipe to add mass to the pipe.