Final answer:
The gases in order of decreasing density at Standard Temperature and Pressure (STP) are Chlorine (Cl₂), Fluorine (F₂), Oxygen (O₂), and Neon (Ne), with Chlorine being the densest and Neon the least dense.
Step-by-step explanation:
To arrange the following gases in order of decreasing density at Standard Temperature and Pressure (STP), we need to know the molar mass of each gas, as density is directly proportional to molar mass under these conditions. The gases given are Oxygen (O₂), Fluorine (F₂), Chlorine (Cl₂), and Neon (Ne).
- Chlorine (Cl₂) - Molar mass = approximately 70.90 g/mol
- Oxygen (O₂) - Molar mass = approximately 32.00 g/mol
- Fluorine (F₂) - Molar mass = approximately 38.00 g/mol
- Neon (Ne) - Molar mass = approximately 20.18 g/mol
Therefore, the gases in order of decreasing density at STP are:
- Cl₂
- F₂
- O₂
- Ne