Students are trying to identify an element that has many of the same physical and chemical properties as sodium (Na) but a larger atomic mass. Which of the following elements could the students be investigating?

Asuspension of yeast cells is being grown under anaerobic conditions such that glucose is degraded to ethanol and carbon dioxide. if one wishes to follow this process by monitoring the release of 14co2, at which positions in the glucose molecule would the 14c label need to be incorporated?