Different metals react differently with acid. Certain metals react very vigorously whilst others react very slowly or not at all. See the reactivity series for this information.
There is a test to test for hydrogen called the squeaky pop test. This involves taking a lit splint to a test tube and if a pop can be heard then hydrogen is present.
The gas produced when a metal and acid react together is hydrogen and it can be seen bubbling off in solution.
Beta