Answer:
C is the only option that represents an empirical formula, as it can't be simplified further.
You can turn C8H18, for example: to C4H9, but you can't do the same with C2H5.
Let me know if this helps!
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<h2><em><u>hope</u></em><em><u> it</u></em><em><u> helps</u></em></h2>
In a pressure cooker, the pressure of the system is in a higher pressure than the pressure outside it. The pressure is caused by the water that is boiling inside the system. The steam that is trapped increases the pressure and as a consequence increases the temperature, cooking the food with less time.
The smallest identifiable unit of a covalent compound is a molecule, which is made up of atoms, e.g. HCl.
The smallest identifiable unit of an ionic compound is a formula unit, which is made up of ions, e.g. Na⁺Cl⁻.