In which of the following reaction, the underlined substance has been reduced
(3)
1) CO+2→CO2+4
2) CuO+2→CuCl2+2
3) H2O+1→H20
4) C0→CO2+4
Only in (3), O.N. of hydrogen decreases from +1 to 0 and hence H2O gets reduced to H2.