The disproportionation redox reaction among the following is :
1
N2(g) + O2(g) → 2NO(g)
2
\(\rm{2Pb(NO_3)_2(s) → 2PbO(s) + 2NO_2(g) + \frac{1}{2} O_2(g)}\)
3
\(\rm{NaH(s) + H_2O(l) \rightarrow NaOH(aq) + H_2(g)}\)
4
\(\rm{2NO_2(g) + 2OH^- (aq) \rightarrow NO_2^- (aq) + NO_3^- (aq) + H_2O(l)}\)