The density of hydrogen is approximately 9 × 10-5 , while the density of helium is approximately 2 × 10-4 . Which of the following is true? A. The density of hydrogen is approximately 20 times the density of helium. B. The density of helium is approximately 20 times the density of hydrogen. C. The density of hydrogen is approximately 2 times the density of helium. D. The density of helium is approximately 2 times the density of hydrogen.