Answer:
Density, 
Explanation:
It is given that, placing a sample of iron (II) oxide into a graduated cylinder makes the water volume increase 12.0 mL.
It means that the volume of the sample is 12 mL
The weight of the sample is 76.6 g
We need to find the density of the sample.
12 mL = 12 cm³
The formula of density is given by :

So, the density of the sample is
.
I believe your answer would be NaOH.
Hope this helps.
What are the choices? I can still help answer but there aren’t any following answers lol
<span>a. a chemical combination of two or more different materials.
For example: </span>For example, air is a mixture of gases, containing N, O, Ar, CO2