Question

Which of the following reactant pairs will not react together to produce a reaction? Li + H2O Fe + Ni(OH)2 Ca + ZnF2 Co + BaCl2

Answer 1

This is an activity series question, and each of the possible reactions involves the oxidation of a metal. What you need to look for is a case where the metal that could be oxidized is less active than what's already oxidized, so nothing will happen.

1) Li is very active and not yet oxidized, so this one will react.

2) Fe is more reactive than Ni.

3) Ca is more reactive than Zn.

4) Co is less active than Ba. Bingo.