Question

If a list of gas is provided, how to know which gas is the closest to ideal gas at STP (standard condition)?

I know He is probably the closest out of all. However, if it is on a multiple choice test, how do I know which one to pick if He is not on there? What makes a gas close to ideal gas at STP? Please explain

Answer 1

Well, you have to make some assessment of the LIKELY intermolecular force....

Explanation:

And so you ask of the individual gases: is there hydrogen bonding (i.e. `HF`, `NH_3`); is there a permanent dipole moment (i.e. `CH_3Cl`); is the molecule massive; how volatile is the gas? All such intermolecular interactions will detract from the ideality of the gas. Certainly, the Noble gases will behave ideally under standard conditions...but then so too will ALL gases...