10) D

Be careful! It specifies “complete combustion of fuels”. This makes the whole difference as we will discuss now.

1 – CH4 is not produced in combustion.

2 – CO is produced in INCOMPLETE combustion

3 – CO2 is produced in combustion as all carbon reacts with the oxygen combustion

4 – H2O is produced as the the hydrogen in the hydrocarbons reacts with oxygen during combustion

5 – He is never produced in combustion

6 – NH3 is not produced