What happens when $CO_2$ is compressed and expanded at a constant temperature of $30.98 \, ^\circ C$?

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:

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

What is the critical temperature $T_C$? What is its value for $CO_2$?

What are the most favourable conditions to liquefy a gas?

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?