Chemistry - Quick question about standard reductions of half-cells

[Fusilli_Jerry89]

my teacher says that if you add acid to the solution then you don't use the H2) half reaction with the (10-7 M), but that you still do if you add a base. Is this true?

[chaoseverlasting]

I don't even know what you're question is... could you please specify what reaction or what is it that youre doing?