Chemical change. You can never get back the rusted layers of metal even though you can wipe off the rust. Chemical changes are irreversible.
Answer is B
It is strongly ionizing and cannot penetrate dense materials.
Negative charge, and the atoms are also called ions in case you need that
Answer is 2
bitanedioic acid has 4 carbon atoms
If gravity is the ONLY force acting on an object, then the force of
Earth's gravity produces acceleration of 9.8 meters per second²
downward. That number doesn't change, and it doesn't depend
on the mass or weight of the object.
If there are any other forces acting on the object at the same time,
like air resistance or some other kind of friction for example, then
all bets are off, and we can't say what the object's acceleration will
be in that case.
