Which metal is resistant to all acids?

--- note the answer is invalid --- Noble metals such as gold, platinium and palladium can be dissolved in aqua regia, a highly concentrated mixture of hydrochloric acid and nitric acid. Silver is soluble in pure nitric acid. Ruthenium can be dissolved in aqua regia only when in the presence of oxygen, while rhodium must be in a fine pulverized form. Niobium and tantalum are resistant to all acids, including aqua regia.