Looking for a short story about a prisoner on a prison planet where prisoners are imprisoned for life with the possibility for release if they can accomplish an assigned "impossible" task.
The task of the protagonist of this story is to invent a universal solvent (there is a conversation when he is given the task between him and the review/parole board about how a universal solvent can't be contained because it would dissolve its own container that I believe ends with the panel indicating that is simply part of the problem to solve).
The story ends with the prisoner requesting (and receiving) a hearing with the review/parole board so he can present the results of his research. (Results of meeting in spoiler below).
After being surprised at his request (because no prisoner ever completes their tasks) the review board agrees to see him and when he arrives they ask him where his universal solvent is and how he managed to solve the "dissolves its own container" problem. He responds by indicating that he manufactured a container which dissolves at a specific rate and he has ingested the container and that the solvent should be breaching the container as they speak. At which point he begins to dissolve and the solvent spreads and dissolves the entire planet.
I would likely have read this somewhere between 1990-2005 though I cannot be certain. It may have been in a short story collection or in an issue of Analog or Asimov's magazines.