1. The problem statement, all variables and given/known data 1) A 5.0- liter gas tank holds 1.7 moles of monatomic helium (He) and 1.10 mole of diatomic oxygen (O2), at a temperature of 260 K. The ATOMIC masses of helium and oxygen are 4.0 g/mol and 16.0 g/mol, respectively. What is the ratio of the root- mean- square (thermal) speed of helium to that of oxygen? A) 2.0 B) 5.6 C) 2.8 D) 4.0 E) 1.4 Answer: C 2) A 25- L container holds ideal hydrogen (H2) gas at a gauge pressure of 0.25 atm and a temperature of 0°C. What mass of hydrogen gas is in this container? The ATOMIC mass of hydrogen is 1.0 g/mol, the ideal gas constant is R = 8.314 J/mol•K = 0.0821 L ∙ atm/mol ∙ K, and 1.00 atm = 101 kPa. A) 1.4 g B) 6.3 g C) 4.2 g D) 2.8 g E) 5.6 g Answer: D 2. Relevant equations Gas law? I don't know. 3. The attempt at a solution I have no idea at all. I would greatly appreciated if you can provide with detailed steps to solve the question. Thank you very much.