Chemistry Help? Balancing Redox???

Question

1. Consider the following skeletal redox reaction:

   Sn²⁺ + NO₂^- --> Sn⁴⁺ + N₂

   Which of the following represents the properly balanced nitrogen half reaction?

   		2 e- + 4 H+ + 2 NO2- --> N2 + 4 H2O
   		4 H+ + NO2- --> N2 + 2 H2O + 3 e-
   		3 e- + 4 H+ + NO2- --> N2 + 2 H2O
   		6 e- + 8 H+ + 2 NO2- --> N2 + 4 H2O