In the reaction ${\mathrm{PCl}}_5 \left(\mathrm{g}\right)\rightleftharpoons {\mathrm{PCl}}_3 \left(\mathrm{g}\right)+{\mathrm{Cl}}_2 \left(\mathrm{g}\right)$, which of the graphs is/are correct?

For the reaction $\mathrm{R}\rightleftharpoons \mathrm{P}$, variation of concentration is plotted against time. The time at which the equilibrium establishes is as shown:

Which of the following regions show(s) equilibrium?

An aquatic species needs at least $4 \mathrm{mg} {\mathrm{L}}^{-1}$ of ${\mathrm{O}}_2$ for their survival. The solubility of ${\mathrm{O}}_2$ in the water at $273 \mathrm{K}$ and $1 \mathrm{atm}$ pressure is $2.21\times {10}^{-3} \mathrm{mol} {\mathrm{L}}^{-1}$. The partial pressure of ${\mathrm{O}}_2$ above water (in the atmosphere at $273 \mathrm{K}$) needed for the survival of species is:

Select the correct statements.