Six astronauts are still on the space station as part of a planned year-long stay in space, the longest tour of duty in the station's 15-year history.
The molecular formula of citric acid is C 6 H 8 O 7. The chemical formula for citric acid is best shown by a diagram of its complete structural formula. This shows how the atoms are arranged in the molecule. Citric acid has three carboxyl or-COOH groups and is triprotic in nature.
The ionic formula of sodium chloride is NaCl. I'm not sure what is meant by structural formula, but there is one chlorine for each sodium atom in the ionic compound.