Which is correct about real gas : 

Among the gases $\mathrm{a}, \mathrm{b}, \mathrm{c}, \mathrm{d}, \mathrm{e}$ and $\mathrm{f}$, the gases that show only positive deviation from ideal behavior at all pressures in the graph are

The volume of gas $\mathrm{A}$ is twice than that of gas $\mathrm{B}$. The compressibility factor of gas $\mathrm{A}$ is thrice than that of gas $\mathrm{B}$ at same temperature. What are the pressures of the gases for equal number of moles?

The isotherms of a gas are shown below :

Among the following,

(i) At ${\mathrm{T}}_1$, the gas cannot be liquefied

(ii) At point $\mathrm{B}$, liquid starts to appear at ${\mathrm{T}}_2$

(ii) ${\mathrm{T}}_{\mathrm{C}}$ is the highest temperature at which the gas can be liquefied

(iv) At point $\mathrm{A}$, a small increase in pressure condenses the whole system to a liquid

The correct statements are :

The variation of the compressibility factor$\left(\mathrm{Z}\right)$with pressure $(\mathrm{P} \mathrm{in} \mathrm{bar})$ for some gases, are shown in the figure below. Identify the gases $\left(\mathrm{A}\right),\left(\mathrm{B}\right)$ and $\left(\mathrm{C}\right)$.