What reactor exploded in chynobl?

The reactor that exploded in Chernobyl was Reactor No. 4 of the Chernobyl Nuclear Power Plant, located near the town of Pripyat in Ukraine. The explosion occurred on April 26, 1986, during a late-night safety test that went wrong, leading to a catastrophic release of radioactive materials. This disaster is considered one of the worst nuclear accidents in history, resulting in widespread contamination and long-term health and environmental impacts.