Re: what liquids expand when frozen?

what liquids expand when frozen?

is water the only liquid to expand when frozen?

What this means is that the solid will float on the liquid. The implication is that you can have oceans of water which are frozen on top but not all the way down.

There is a good bit of old science fiction about cold planets with oceans of ammonia, but if they ever froze, they'd freeze for good because they'd freeze from the bottom up.

Additional heat (applied from the top, of course) on a partly frozen ammonia ocean would vaporize the surface layer before it would melt the frozen stuff at the bottom. But a water ocean can thaw completely before it starts boiling away because the ice is always at the top.