What is critical temperature? How will you differentiate between a gas and a vapour depending on critical temperature?

What is critical temperature? How will you differentiate between a gas

1.	What is critical temperature? How will you differentiate between a gas and a vapour depending on critical temperature?
Answer» The temperature above which a gas connot be liquefied, no matter how great the pressure is called critical temperature. If the substance lies above the critical temperature then it falls in the gaseous region. If the substance lies below the critical temperature than it falls in the vapour stage.