If you have a black background and a white line in the middle, why does the white line appear to be white?

What is the chemical formula of the following compound

Consider the following reactions. (note: (s) = solid, (l) = liquid, and (g) = gas.) mg(s) + ½o2(g) → mgo(s) + 146 kcal/mole h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal/mole what type of reaction is represented by the previous two examples?

What is the molar mass of a gas that has density of 2.054 g/l