1. A ____________ contains only one kind of atom.
2. How is a compound formed?
3. There are millions of compounds. True or False?
4. Write the formulae for the following compounds:
a. water b. carbondioxide c. ethanol
5. How is a mixture different from a compound?
6. How can you separate a mixture of iron and sulfur?
7. Sulfur dissolves in _________.
8. What happens when a mixture of iron powder and sulfur is heated? Write an equation.
9. Write three signs that a chemical change has taken place.
10. A chemical change is also called a _____________.
11. Is burning gas while cooking a chemical reaction? How do you know?
12. Mixing iron powder with sulfur is a physical change. Give two reasons why you think so.
13. Dissolving sulfur in methylbenzene is a ___________ ( physical/chemical) change. Is it reversible?
14. Separating iron filings by filtering is a ________ ( physical/chemical) change.
15. If no new chemical substance is formed, it is a _______ ( physical/chemical) change.