Final answer:
Cell B3 should contain the quantity of a specific element corresponding to the 'Element' in B1, following data organization practices for clarity in spreadsheets.
Step-by-step explanation:
According to best practices for data organization in spreadsheets, cell B3 in Figure 2 should ideally contain a piece of data that corresponds to the labeled 'Element' in row 1 of the spreadsheet, as well as relates to the 'Quantity' in row 2. Since the provided figures and context do not specify the exact content of Figure 2, a direct answer for what should be in cell B3 cannot be given without additional information. However, in a well-organized spreadsheet following good data organization principles, cell B3 would most likely contain the number of atoms for a specific element when referencing a chemical compound's composition, as seen in the given examples of chemical tables in the question. In such a table, 'Quantity' would refer to how many atoms of each 'Element' are present in a molecule, and the multiplication across rows would give the 'Subtotal (a m u)' for each.