<span>A spectator ion is an ion that exists in the same form on both the reactant and product sides of a chemical reaction.</span>
Answer
Sounds travel slowest in gasses so it would be air
The chemical reaction is written as:
2Zn + O2 = 2ZnO
We are given the amount of the product to be produced from the reaction. We use this value and the relation of the substances in the reaction to calculate what is asked. We do as follows:
2.10 g ZnO ( 1 mol / 81.408 g ) ( 1 mol O2 / 2 mol ZnO ) ( 32 g / 1 mol ) = 0.414 g O2 is needed
I believe it is b. you only want to change one thing at a time so you know which one thing caused the effect