if the voltage of the cell is 2.0898V at 25C when [Mg2+] = 0.1945M and the pressure of H2 = 1.00atm, what is the pH? E0=2.3700V

Mg(s)+2H+(aq)<--> Mg2+(aq)+ H2(g)

Ecell = Eocell -(0.0592/2)*log Q.

Substitute the values from the problem and solve for H^+ (a part of Q). Convert to pH.