Final answer:
To rank gases in order of increasing density at STP, the molar mass is used because the molar volume is constant. CH4, with the lowest molar mass, is the least dense, followed by N2, C4H10, and Xe as the densest.
Step-by-step explanation:
To rank the gases Xe, N2, CH4, and C4H10 in order of increasing density at STP (Standard Temperature and Pressure), we need to consider the molar mass of each gas since the molar volume of a gas at STP is constant (22.4 L/mol). The density of a gas is directly proportional to its molar mass under these conditions.
- Molar Mass of N2: Approximately 28 g/mol
- Molar Mass of CH4: Approximately 16 g/mol
- Molar Mass of Xe: Approximately 131 g/mol
- Molar Mass of C4H10: Approximately 58 g/mol
Therefore, the correct order from least dense to most dense is: CH4 < N2 < C4H10 < Xe.