Question

Another real-world example of a change is rust. Rust is iron oxide (Fe2O3), which results when iron is exposed to oxygen in the air.
What are some indicators of rusting? Check all that apply.

production of light

color change

formation of a solid

formation of a gas

Answer 1

Formation of a solid and color change!

Answer 2

Answer: Color change and the formation of a solid are the indicators of rusting.

Explanation: Rust is a red colored compound known as iron oxide ( $Fe_2O_3$ ) which is formed when iron comes in contact with oxygen. Equation for rusting follows:

$4Fe(s)+3O_2(g)\rightarrow 2Fe_2O_3(s)$

Iron metal is grey in color and the oxide formed is red in color.

As seen from the above equation, a solid compound is formed, so we can say that the indicators of rusting are : Color change and formation of a solid.