What is the dependent and independent variable in this experiment?

There are 4 test tubes with nails inside

1 - test tube with air and water

2 - water but no air

3 - water, air and salt

4 - just air, no water



After leaving nails in test tube for 3 days...

The nails in test tube 2 and 4 do not rust. Nails in test tube 1 and 3 rust.



What is the dependent and independent variable?



thanks in advanceWhat is the dependent and independent variable in this experiment?
The independent variable is what you can change to set up the expt; presence of water, of salt



the dependent variable is what varies a a result; amount of rusting.



that's all!