1) A Car engine.............. Hope it helps, Have a nice day :)
The complete chemical formula for the unknown compound will be 
<h3>Chemical formula</h3>
The chemical formula of the compound is
and x is supposed to be a whole number.
In the analysis, C = 2.22 moles and H = 6.7 moles
Dividing both by the smallest: C = 1 and H = 3
Thus, the empirical formula of the compound will be 
But since the compound is
, it means both C and H are multiplied by 2.
The chemical formula will, therefore, be 
More on chemical formulas can be found here: brainly.com/question/11995171
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