How is incomplete combustion different to complete combustion

All of the fuel is not used

Explanation:

In complete combustion, there is enough oxygen present to “burn” all of the carbon fuel. By contrast, there is not enough oxygen available to burn all of the carbon fuel in the process of incomplete combustion.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

answer; the numbers of valence electrons in the acetic acid molecule (ch3co2h) is 24;