Multiple ChoiceIn the following diagram, the element with atomic number 8 is represented by a question mark. Which element's symbol should replace the question mark?27views
Multiple ChoiceIn the periodic table, the element manganese is represented by a box containing the symbol 'Mn'. If an arrow is pointing to 'Mn', what does this symbol indicate?35views
Multiple ChoiceWhich element is in the same period as ruthenium (Ru) but has a higher atomic number than ruthenium?38views