Hydrogen Sulphide, To ask for a help in Chemistry in such questions is a contrary to your name(H2S). While you register for the class, if you have noticed or not, there is a thing called "academic Honesty". I am sure that posting such thing asking for helo to enhance your grade is totally against the academic Honesty also note that professors are very serious about such sorts of matter. As being one of your best wishers, I suggest you to go through some basic general chemistry to find the solution rather than pleading for help in public forum like Sajha.