<u>Answer:</u> The correct option is
<u>Explanation:</u>
A catalyst is defined as the chemical species that increases the reaction rate but does not participate in it and is left behind after the completion.
A homogeneous catalyst is one that is present in the same phase as the reactants and products.
A heterogeneous catalyst is one that is present in different phase as that of reactants and products.
For the given chemical reaction:

As all the reactants and products are in gaseous state so, the homogeneous catalyst must also be in the gaseous state only.
Hence, the correct option is 
Just use a solubility chart! Find the cation on the far left and the anion on the top and find where they connect. If it says "s," it is not soluble. If it says "aq," it is soluble. Here, ZnF (Zinc Fluoride) is soluble. Hope that helps! :)
P.S. Not all of the compounds above are on this particular chart. In future problems, just google "solubility chart" until you find one with all of the compounds you need to look at.
Answer:
125 cubic meters
Explanation:
Subtract 375-250=125 cubic meters
simple molecules contain two atom bonded together
the Equator receives the most solar energy