Among the following, select the disproportionation reaction ?(i) 2PbNO32 →  2PbO+ 4NO2 + O2(ii) I2 →  I- + IO3-(iii) 3Cl2 + 6NaOH →  5NaCl + NaClO3 + 3H2O(iv) P4 + 3NaOH + 3H2O→  3NaH2PO2 + PH3

A reaction in which the same species is simultaneously oxidized as well as reduced is called a disproportionation reaction.(ii) I20 →  I--1 + IO3-+5(iii) 3Cl20 + 6NaOH →  5NaCl-1 + NaClO3+5 + 3H2O(iv) P40 + 3NaOH + 3H2O→  3NaH2P+1O4 + P-3H3