Yes... that is correct.
CH4 is methane so the coefficent in front of it would double the number of atoms of each element
We know that acids have a pH of under 7.
We also need to:
Set up an ICE table for the chemical reaction. Solve for the concentration of H3O+ using the equation for pH Use the concentration of H3O+ to solve for the concentrations of the other products and reactants.
I believe a hydrochloric gas will be let off