https://sciencing.com/make-3d-model-atom-5887341.html
I will have to go with carbon monoxide
Answer:
What do you mean what happened?
Explanation:
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Answer: The correct option is 3.
Explanation: We are given a compound which is made up of iron and oxygen only. The ratio of the two are given as:

This means that, number of iron ions are 2
Number of oxide ions are 3
From the above information, the formula becomes : 
The valency of iron = 3
Valency of oxide = 2
This compound is named as iron (III) oxide.
Hence, the correct option is 3
N⁻²2H4(l) + 2H2O⁻¹2(l) → N⁰2(g) + 4H2O⁻²(g)
N is oxidized and O is reduced