Question

butane to 1,3butadiene​

Answer 1

Answer:

comparison without actual data should be possible. 1,3-butadiene is conjugated so it is the most stable compound and therefore its heat of hydrogenation should be the smallest

No, 1,3-butadiene is not the most stable of these compounds, either for the whole molecule or on a per double bond basis (see below). The actual numbers (see table below) are too close, we need to look at some data in order to answer the question correctly.

The question asks us to select the compound with the smallest heat of hydrogenation per mole out of the following:

So would we consider each heat of hydrogenation "per mole of hydrogen" or "per mole of the given compound"?