P is an aqueous solution of acid and Q is an aqueous solution of base. When these two are diluted separately, then

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. 

If a few drops of a concentrated acid accidently spill over the hand of a student, what should be done? 

On passing ${\mathrm{CO}}_2$ gas in excess in aqueous solution of sodium carbonate, the substance obtained is