Rust forming on a piece of iron is an example of which of the following: A: A physical change because the process can be reversed
B: The natural process of decay as metallic ions age
C: A chemical change because oxygen atoms from the atmosphere bonded with the iron atoms
D: A violation of the laws of physics because new mass has been created

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.

to improve her experimental investigation, dalila should add a row in which no fertilizer is used. by a having a contrasting row in which no fertilizer is used, she will have a control group that will her understand the effects of the fertilizer in the plant developments vs the development of the plant when no fertilizer is used.