Final answer:
The Decembrists were punished by executing five of their leaders and exiling the rest to Siberia, where many were subjected to hard labor in penal colonies.
Step-by-step explanation:
The Decembrists were a group of Russian army officers who led an uprising against Tsar Nicholas I in December 1825, aspiring to implement liberal reforms in Russia. After the revolt failed, the Decembrists were severely punished. Specifically, five were executed, while the others were exiled to Siberia, where many of them were subjected to hard labor in the katorga prison camps. This punishment was indicative of the tsarist regime's intolerance of dissent and became an early example of how the state would deal with political prisoners.