In three moles of ethane (C2H6), calculate the number of moles of carbon atoms.

The correct option is 6.

To find the number of moles of carbon atoms in three moles of ethane ($C_2{H}_6$), we can analyze the chemical formula of ethane step-by-step:

1. Examine the molecular formula of ethane, which is $C_2{H}_6$. This formula indicates that each individual molecule of ethane contains exactly 2 carbon (C) atoms and 6 hydrogen (H) atoms.
2. Scaling this up to the molar level, 1 mole of ethane ($C_2{H}_6$) molecules contains exactly 2 moles of carbon atoms.
3. Therefore, to find the number of moles of carbon atoms in 3 moles of ethane, we multiply the number of moles of ethane by the number of carbon atoms per mole of ethane:

$\text{Moles of carbon atoms}=3\text{moles of}{C}_2{H}_6\times \frac{2\text{moles of C}}{1\text{mole of}{C}_2{H}_6}$

$\text{Moles of carbon atoms}=6\text{moles}$

Thus, three moles of ethane contain 6 moles of carbon atoms.