The correct options are
A Chernobyl disaster in Ukraine was caused by leakage of Diborane.
B Union Carbide treated its waste before expelling it into the environment after the Bhopal tragedy.
The Chernobyl disaster was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in the city of Pripyat, then located in the Ukrainian Soviet Socialist Republic of the Soviet Union. The Chernobyl disaster was the worst nuclear power plant accident in history in terms of cost and casualties. Ever since the accident, Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and compensation costs of the Chernobyl accident.Even after the Bhopal gas tragedy, Union Carbide expelled untreated poisonous wastes into the environment and when it finally quit Bhopal in 1998, it left behind around 5,000 tons of deadly waste. Dow Chemicals, which purchased Union Carbide, has refused to clean up the site, provide safe drinking water, or compensate the victims.