Question

Which of these reactions are redox reactions? Check all that apply.

Answer 1

Cd + HCl → CdCl2 + H2
2ZnS + 3O2 → 2ZnO + 2SO2 

CH4 + 2O2 → CO2 + 2H2O

Answer 2

 The  reaction  that  are   redox  reaction  are

 Cd  +HCl  →  CdCl2  +H2

2 ZnS  +3 O2→ 2 ZnO  + 2  SO2

CH4  +2O2→ CO2 + 2 H2O

Explanation

A  redox  reaction is a  type of  reaction  which involve  both  reduction  and  oxidation.

Cd +HCl → CdCl2 +H2  is a redox  equation  because

 Cd is  oxidized   from  oxidation state   0 to  2+  while H  is  reduced from oxidation state  1 t o 0

All combustion reaction   are redox reaction  therefore

2 ZnS  + 3 O2 → 2ZnO + 2 SO2

    and

CH4 +2 O2 →  CO2 + 2 H2O  are  redox reaction