So for example, for this isomer of hexane, we have negative ten kilo cals per mole of change in enthalpy of formation. And we see that as we go from one to five, our values become more and more negative. And five is the most stable isomer and one is the least stabilizomer. So stability increases as we go down from one to five. So why is that? Why is it that number one is less stable than number five?