What is critical temperature $(T_{C})$?

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

The isotherms of a gas are shown below:
Among the following:
$(i)$ At $T_1$,the gas cannot be liquefied.
$(ii)$ At point $B$,liquid starts to appear at $T_2$.
$(iii)$ $T_c$ is the highest temperature at which the gas can be liquefied.
$(iv)$ At point $A$,a small increase in pressure condenses the whole system to a liquid.
The correct statements are:

The gas with the highest critical temperature is

What is the Andrews isotherm graph used for?

What is meant by the vapor of a substance like $CO_2$?