Прочитайте текст.
Marie and Pierre Curie knew that radium existed, but they had to prove it because a chemist believes in the existence of a new substance after seeing it, touching it, weighing it and finding out its atomic weight. They began working at that problem in 1898. Their task was to obtain pure radium. The way to separating radium was a difficult one. They could separate radium by treating large amounts of pitchblende.
In 1902 they succeeded in preparing a decigram of pure radium. Radium had something better than a beautiful colour, it was luminous. The discovery of radium gave them the possibility of discovering other radioactive substances.
Ответьте на вопрос:
What colour was radium?