Question

Which metals may be oxidized by H+ under standard-state conditions? Ag+(aq) + e– → Ag(s) E° = 0.80 V Cu2+(aq) + 2e– → Cu(s) E° = 0.34 V Sn2+(aq) + 2e– → Sn(s) E° = –0.14 V Zn2+(aq) + 2e– → Zn(s) E° = –0.76 V

Answer 1

Answer is: tin and zinc, because they standard potential as less than zero.
Tin and zinc are oxidized to tin and zinc cations (with +2 charge) and hydrogen anions are reduced to hydrogen molecules with neutral charge.
Zn → Zn²⁺ + 2e⁻; 2H⁺ + 2e⁻ → H₂.
Oxidation is increase of oxidation number  and reduction is decrease of oxidation number.