1. Did the accident at the Chornobyl nuclear power plant Ukraine in 1986 cause radioactive contamination of a vast area around the plant?
2. Did the accident at the Chornobyl nuclear power plant Ukraine 1986 or 1987 cause radioactive contamination of a vast area around the plant?
3. What caused radioactive contamination of a vast area around the plant?
4. When did the accident at Chornobyl nuclear power plant cause radioactive contamination of a vast area around the plant?
5. The accident at the Chornobyl nuclear power plant Ukraine in 1986 caused radioactive contamination of a vast area around the plant, didn't it?