Hi, I'm in 12th grade and for my senior project I wanted to do an experiment on the effects that copper and zinc have on mung beans.

I have copper sulfate pentahyde and zinc sulfate monohydrate, which I had purchased because I have seen information on other similar experiments where these were used to test the effects of copper and zinc on plants. I was wondering whether I should instead use copper powder and zinc powder instead as these, I think, would make for better variables because they are purer forms of metal.

Aside from this, I have had trouble deciding what amounts to use on the plants and whether I should add the amounts to the soil directly before planting or make a solution with water and use it as the plants' water source throughout the experiment. I was planning on using 24 plants for the copper part of the experiment with six groups of four plants, with the first group of four being the control group and the next five groups having increasing amounts of the heavy metal. The same would be done for the zinc portion. 

Any thoughts or suggestions would be appreciated. Thank you very much.

Make couple well-known solutions with the same compound (different amount of water + the same amount of compound). Add them to plants. Leave control group without any additions.

ps. If you are unsure what to do you should ask your tutor for explanation, or explain him/her what you intend to do, and ask if it's the correct way to perform experiment.