Which sample contains more molecules: 2.0 L of Cl₂ at STP or 3.0 L of CH₄ at 300 K and 1150 mmHg? Which sample weighs more?

A gas has a volume of 2.84 L at 1.00 atm and 0 °C. At what temperature does it have a volume of 7.50 L at 520 mmHg?

How many molecules are in 1.0 L of O₂ at STP? How may grams of O₂?

What is the mass of CH₄ in a sample that occupies a volume of 16.5 L at STP?

A weather balloon is partially filled with helium to allow for expansion at high altitudes. At STP, a weather balloon is filled with enough helium to give a volume of 25.0 L. At an altitude of 30.0 km and ―35 ⁰C, it has expanded to 2460 L. The increase in volume causes it to burst and a small parachute returns the instruments to Earth. (8.5, 8.6)b. What is the final pressure, in millimeters of mercury, of the helium inside the balloon when it bursts?

Using the answer from problem 8.61, how many grams of nitrogen are in Whitney's lungs at STP if air contains 78% nitrogen?