We’re being asked to determine if the recorded substance is a new element judging from this figure
We will first determine the element based on the description and determine if a new element was discovered.
The description of the substance is
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: 153 oC. 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 800 oC."
Judging from the figure, might this nineteenth-century investigator have been the first to discover a new element?