A historian discovers a nineteenth-century notebook in which some observations, dated 1822, were recorded on a substance

Question:

A historian discovers a nineteenth-century notebook in which some observations, dated 1822, were recorded on a substance thought to be a new element. Here are some of the data recorded in the notebook: "Ductile, silver-white, metallic looking. Softer than lead. Unaffected by water, Stable in air melting point: 153oC density: 7.3 g/cm3. Electrical conductivity: 20% that of copper. Hardness: About 1% as hard as iron. When 4.20 g of the unknown is heated in an excess of oxygen, 5.08 g of a white solid is formed. The solid could be sublimed by heating to over 800oC."
(a) Using information in the text and the CRC Handbook of Chemistry and Physics, and making allowances for possible variations in numbers from current values, identify the element reported.
(b) Write a balanced chemical equation for the reaction with oxygen.
(c) Judging from Figure 7.1, might this nineteenth-century investigator have been the first to discover a new element?