Which one of the following is the correct $PV$ vs $P$ plot at constant temperature for an ideal gas? ($P$ and $V$ stand for pressure and volume of the gas respectively)

An ideal gas $(X)$ present in a vessel of volume $V \ L$ exerted a pressure of $16.4 \ atm$ at $200 \ K$. What is its concentration in $mol \ L^{-1}$? (Given $R=0.082 \ L \ atm \ mol^{-1} \ K^{-1}$)

According to Charles's Law,what is the slope of the graph of volume versus temperature? ($V_0$ is the volume of the gas at $0\,^{\circ}C$ and $V_t$ is the volume of the gas at $t\,^{\circ}C$)

At what temperature does the volume of a gas become theoretically zero?

For a fixed amount of gas at a constant temperature,which of the following is true?

Pay load is defined as the difference between the mass of displaced air and the mass of the balloon. Calculate the pay load when a balloon of radius $10 \, m$,mass $100 \, kg$ is filled with helium at $1.66 \, bar$ at $27^{\circ} C$. (Density of air $= 1.2 \, kg \, m^{-3}$ and $R = 0.083 \, bar \, dm^{3} \, K^{-1} \, mol^{-1}$).