H2O→H2→H2O→O2->CuO->C4

Question

H2O→H2→H2O→O2->CuO->C4

Answer 1

2H2O + Ca -> Ca(OH)2 + H2

2H2 + O2 -> 2H2O

2H2O -> 2H2 + O2

2Cu + O2 -> 2CuO

2CuO -> 2Cu + O2