N2 + ___ H2 --> NH3
Reaction :

N2 +H2 →2 NH3

"Reactants Products Nitrogen 2 2 Hydrogen 2 6 Since NH3 is multiplied by a coefficient of 2 there are now 2 nitrogens and 6 hydrogens. The 6 hydrogens come from the 2 multiplied by the subscript of 3."

- "the choice that is not an indicator of a chemical change is "state of matter changes". more common than not, chemical reactions produce energy in the form of light or heat. along with energy, they also produce a new substance called the product that could be in any state of matter (solid, gas, or liquid)."

i think   the answer is c hope i'm right