On adding a few drops of Universal indicator solution to three unknown colourless solutions $\mathrm{P}, \mathrm{Q}$ and $\mathrm{R}$ taken separately in three test tubes shown in the diagrams, a student observed the changes in colour as green in solution $\mathrm{P}$, red in solution $\mathrm{Q}$ and violet in solution $\mathrm{R}$.

The decreasing order of $\mathrm{pH}$ of the three solutions is: