Answer. Statement second and third both are correct.
Explanation: When iron(grey) reacts with sulfur(yellow) chemical change takes place in which iron sulfide is formed which black in color.

When we heat copper sulfate-pentahydrate(blue) ,water molecule present in its crystal will get evaporated and it will become an anhydrous copper sulfate which will be white in color.

So, in both the reactions change in color and change in chemical arrangement has taken place.
Answer:
I think it's C but I'm atlessy 60% sure :]
<span>CO2 (carbon) is the main product that results from burning paper. The paper is the reactant
When paper burns in a fire, the reactants are mostly carbon (the main substance in the paper) and oxygen (from the air).Co2
If paper is loaded with CaCO3 such as cigarette paper, CaCO3 decompose in to CaO and CO2</span>
An insoluble solid formed during a reaction is called a Precipitate.