Answer : The number of moles of hexane is, 3.06 moles
Explanation : Given,
Moles of carbon dioxide = 18.4 mole
The balanced chemical reaction will be,

From the balanced chemical reaction, we conclude that 2 moles of hexane react with 19 moles of oxygen gas to give 12 moles of carbon dioxide gas and 14 moles of water as a product.
As, 12 moles of carbon dioxide obtained from 2 moles of hexane
So, 18.4 moles of carbon dioxide obtained from
moles of hexane
Therefore, the number of moles of hexane is, 3.06 moles