Questions 19-24 For each question, choose the correct answer.

Here are the answers to the questions, based on the provided text:

1. 19: B (subject) - "But it was the subject of chemistry that really interested him."
2. 20: B (trying) - "While he was there, he was trying to make a medicine from coal."
3. 21: A (way) - "When he was working on the problem, he found a cheap way to make the colour purple."
4. 22: B (time) - "At that time it was very expensive to make clothes in different colours."
5. 23: C (opened) - "He opened his own factory to make the colour."
6. 24: C (became) - "...and soon purple clothes became very popular in England and the rest of the world."