See, I think that's fantastic homework, for exactly the same reasons you thought it was bad. Sparks interesting and pertinent discussion about exactly what reversible ought to mean.
For middle school or high school science, yeah-- awesome and thought-provoking. I used to ask some of this same stuff of college freshman, fwiw. They found it somewhat challenging to consider, for the reasons that Nautigal notes.
Oh, yes, it would be fascinating for older kids or college students -- it has a lot of good head-scratchers. But as a worksheet for 2nd graders trying to learn the words, it's worse than useless! I'm imagining a foreign-language class, where they give you that language's word for "irreversible" (or "mixture"?) and show you a picture of a pizza.
Elizabeth, thanks, but no, the one I was looking for is actually titled "The Ultimate Bad Homework Question Thread" or something close to that. It seems to have fallen off the backside.
