c) If a mixture of zinc powder and cobalt(II) oxide is heated, the following reaction occurs: Zn(s) + COO(s) → ZnO(s) + Co(s) (i) Which metal is higher in the reactivity series? (ii) The zinc can be described as a reducing agent. Using this example, explain what is meant by the term 'reducing agent'. (iii) Which substance in this reaction has been oxidised? ​