9. (1 pt) Roasting galena (lead (1) sulfide) in oxygen gas is an early step in the industrial isolation of lead metal. How many liters of sulfur dioxide, measured at STP, are produced by the reaction of 5.06 kg of galena with 350. L of Oz at 250.*C and 4.00 atm. (Hint: Write out the reaction; the other product is lead (II)oxide.) 10. (pt) A 1.00 mole sample of an unknown gas at STP effuses in 13.6 minutes. An equal volume of H2 gas in the same apparatus under the same conditions effuses in 2.78 minutes. What is the molar mass of the unknown gas? (Hint: The rate of effusion can be thought of as having units of moles per minute)