16. In the chemical formula for water, H2O, what does the “2” mean?
There are two oxygen (O) atoms in a molecule of water.
There are two hydrogen (H) atoms in a molecule of water.
The hydrogen in water is actually deuterium.
17. What elements do the symbols H, O, C, and N stand for?
hydrogen, ozone, carbon, nitrogen
hydrogen, oxygen, chlorine, nitrogen
hydrogen, oxygen, carbon, natrium
hydrogen, oxygen, carbon, nitrogen
18. What elements do the symbols Fe, Na, Au, and Hg stand for?
aluminum, nitrogen, silver, tungsten
iron, sulfur, silver, ytterbium
iron, sodium, silver, mercury
iron, sodium, gold, mercury
19. How many elements have been identified?
20. The buoyant force that keeps a ship afloat is an example of