The answer to your question is option 1. I hope this has helped.
Answer:
Redox type
Explanation:
The reaction is:
2Cr + 3Fe(NO₃)₂ → 2Fe + 2Cr(NO₃)₃
2 moles of chromium can react to 3 moles of iron (II) nitrate in order to produce 2 moles of iron and 2 moles of chromium nitrate.
If we see oxidation state, we see that chromium changes from 0 to +3
Iron changed the oxidation state from +2 to 0
Remember that elements at ground state has 0, as oxidation state.
Iron is being reduced while chromium is oxidized. Then, the half reactions are:
Fe²⁺ + 2e⁻ ⇄ Fe (Reduction)
Cr ⇄ Cr³⁺ + 3e⁻ (Oxidation)
When an element is being reduced, while another is being oxidized, we are in prescence of a redox reaction.
Three is simply the coefficient which tells you the amount of molecules. In this case, there are three carbon dioxide molecules. If you want to break it down further, it also means there is three carbon atoms and six oxygen atoms.
I hope this helps.