Which of the following graphs shows the change in pH when zinc carbonate is added to hydrochloric acid until it is in excess?

Which of the following solutions has the lowest pH value? 

In an experiment, $5 {\mathrm{cm}}^{-3}$ of $1.0\mathrm{mol}/{\mathrm{dm}}^3\mathrm{NaOH}$ solution is gradually added to $10{\mathrm{cm}}^3$of $1.0\mathrm{mol}/{\mathrm{dm}}^3\mathrm{HCl}$ solution containing methyl orange indicator.

Which of the following changes will occur in the mixture? 

pH of different solutions are given in the table. 

Arrange these solutions in the increasing order of ${\mathrm{OH}}^{-}$ ion concentration.