$A, B, C$ and $D$ are four different gases with critical temperatures $304.1, 154.3, 405.5$ and $126.0 \ K$ respectively. While cooling the gas,which gets liquefied first?

Which of the following gases is most difficult to liquefy?

Why does the boundary between the liquid phase and the gaseous phase disappear upon heating a liquid up to the critical temperature in a closed vessel? In this situation,what will be the state of the substance?

Which statement$(s)$ is/are applicable above critical temperature?

What is the value of the critical temperature of water (in $K$)?

The number of statements,which are correct with respect to the compression of carbon dioxide from point $(a)$ in the Andrews isotherm from the following is $..........$.
$A.$ Carbon dioxide remains as a gas up to point $(b)$
$B.$ Liquid carbon dioxide appears at point $(c)$
$C.$ Liquid and gaseous carbon dioxide coexist between points $(b)$ and $(c)$
$D.$ As the volume decreases from $(b)$ to $(c)$,the amount of liquid decreases