Apply the pH scale to compare the levels of acidity or alkalinity of aqueous solutions.

A student measures the pH of four aqueous solutions at 298 K using a calibrated pH meter. The results are: Solution A, pH = 2.8; Solution B, pH = 7.0; Solution C, pH = 10.5; Solution D, pH = 12.2. Which solution contains the lowest concentration of hydrogen ions, $[\text{H}^{+}]$?

Two colourless aqueous solutions were tested at $25 \text{ °C}$. Solution A contains $1.0 \times 10^{-3} \text{ mol/L}$ of hydrogen ions. Solution B has a measured $\text{pH}$ of $11.2$. (a) Calculate the $\text{pH}$ of Solution A. (b) Identify which solution is more alkaline and explain your answer using the $\text{pH}$ scale.