Question: what are the physical properties of technetium?
Answer: Technetium is a silvery-gray transition metal. It tarnishes slowly in moist air. It dissolves in nitric acid, aqua regia (nitro-hydrochloric acid) and concentrated sulfuric acid, but is not soluble in any strength of hydrochloric acid. Technetium's common oxidation states are +7, +5, and +4.