References

1)longman complete guide to 'o' level chemistry book

2)Science in focus chemistry for GCE 'o' level

3)Chemistry matters teacher's edition workbook

4)Lower secondary science (EPH)

5)http://www.answers.com/

6)http://www.ric.edu/faculty/ptiskus/chemical/

7)http://www.mcwdn.org/chemist/pcchange.html

8)http://chemistry.about.com/od/lecturenotesl3/a/chemphyschanges.htm