What is the element presented, in this compound?

test: a small amount of the sample is mixed with cupric oxide in a test tube. the test tube is heated and the issuing gas is passed through a saturated solution of baric hydroxide.
observation: the solution turns cloudy.
test: a small amount of sample is added to sodium metal in a fusion tube and heated. the test tube is then plunged in to a distilled water bath. the fusion tube breaks. the content of the fusion tube is then dissolved in the distilled water, using a glass rod. the solution thus obtained is boiled and filtered. freshly prepared solution of sodium nitroprusside is added to about 1 milliliter of the filtered solution.
observation: the color of the solution turns violet.
test: a compound is fused with sodium peroxide and extracted with water. this solution is heated with nitric acid and ammonium molybdate solution.
observation: a yellow colored precipitate results.