Stability of ortho- and para-hydrogen

1. can the stability of *ortho*-hydrogen greater than *para*-hydrogen can be stated as this?



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> The intrinsic energy of *ortho* is greater than *para*-hydrogen and also with rise in temperature %of *ortho* form increase while *para* decreases and ultimately at room temperature it's 75% *ortho* and 25% *para*-hydrogen. Plus as we know that the everything in nature tries to attain lowest possible energy level, and *ortho* form with opposite spins counteracts each others magnetic moments, making it energetically stable.
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2. Why is it that pure *para* can be obtained at lower temperature such as 20 K but pure *ortho* form is difficult to obtain? 


I mean when *ortho* is more stable it should be *ortho* which should be available more easily than *para* form?




From ["Statistical Mechanics: A Concise Introduction for Chemists"](http://rads.stackoverflow.com/amzn/click/0521009669) by Benjamin Widom (pp. 35-36):



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> For the diatom of ordinary hydrogen ($\ce{{}^{1}\_{1} H}$), where each
>  nucleus is just a proton of spin quantum number 1/2, there are three
>  possible symmetric states of the pair of spins (nuclear spin triplet)
>  and only one possible antisymmetric nuclear spin state (spin
>  singlet). [...]
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> At high temperatures, which generally means $T \gg
> > \theta\_{\mathrm{rot}}$ (where $\theta\_{\mathrm{rot}}$ is the
>  characteristic rotational temperature) and so for $\ce{H2}$ means $T$
>  well above 88 K, the three ortho nuclear-spin states and one para
>  state are equally populated, so equilibrium hydrogen at high
>  temperatures is a mixture of ortho- and para-hydrogen in the ratio
>  3:1. In pure hydrogen the magnetic interactions between molecules that
>  could cause transitions between nuclear spin states are so weak that
>  such hydrogen may be cooled to arbitrarily low temperatures with the
>  ortho:para ratio remaining 3:1. That is normal hydrogen. Paramagnetic
>  impurities such as $\ce{O2}$, or a catalyst such as $\ce{Pt}$ on the
>  surface of which $\ce{H2}$ molecules may dissociate, allowing the
>  atoms to recombine with their nuclear spins in a different relative
>  orientation, catalyze the ortho-para conversion. Cooled in the
>  presence of such a paramagnetic impurity or such a catalyst, then, the
>  hydrogen may have its ortho:para ratio continually adjust to that
>  which would correspond to thermal equilibrium at the given low
>  temperature. [...]
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> Cooled in such a way, then, hydrogen becomes pure para-$\ce{H2}$ at
>  low temperatures, in contrast to "normal" hydrogen, which remains a
>  mixture of ortho and para in the ratio 3:1. If the hydrogen is cooled
>  in the presence of a catalyst that catalyzes the ortho-para conversion
>  and thus allows it to become pure para-$\ce{H2}$ at low T, and if the
>  catalyst is then removed and the hydrogen warmed back up to 298 K,
>  say, the result is a sample of pure para-$\ce{H2}$ at normal
>  laboratory temperatures. Pure ortho-$\ce{H2}$ cannot be prepared in
>  this way.
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