Across
- 1. Which orange greens as it oxidizes?
- 4. What do humans and fish breathe?
- 5. What is commonly found in commercial salt?
- 6. What caused watch factory shutdowns in the early 1900's?
Down
- 2. Which element was discovered in 1898 by Marie Curie and her husband but is not radium?
- 3. Which gas is commonly used in colorful light fixtures?