試題詳解

13. Helium effuses through a small opening at a rate of 1×10⁻⁹ mol s⁻¹. An unknown gas at the same temperature and pressure is found to effuse through the same opening at a rate of 3.78×10⁻¹⁰ mol s⁻¹. What is the molecular mass of the unknown gas?
(A) 4 g mol⁻¹
(B) 14 g mol⁻¹
(C) 18 g mol⁻¹
(D) 28 g mol⁻¹
(E) 40 g mol⁻¹