This is an incomplete question, here is a complete question.
The following balanced equation shows the formation of ethane (C₂H₆).

How many moles of hydrogen are needed to produce 13.78 mol of ethane?
1) 3.445 mol
2) 6.890 mol
3) 27.56 mol
4) 55.12 mol
Answer : The number of moles of hydrogen needed are, (3) 27.56 mol
Explanation : Given,
Moles of ethane = 13.78 mol
The given balanced chemical reaction is:

From the balanced chemical reaction we conclude that,
As, 1 mole of ethane produced from 2 moles of hydrogen
So, 13.78 mole of ethane produced from
moles of hydrogen
Thus, the number of moles of hydrogen needed are, 27.56 mol