The $.........$ of the molar concentration of $[H_3O^+]$ in an acidic aqueous solution is called the $pH$ of that solution.

The aqueous solution having $pH \, 11$ is how many times more basic than an aqueous solution having $pH \, 8$?

$A$ sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the $pH$ paper yellowish-orange. Which of the following would change the colour of this $pH$ paper to greenish-blue?

Which of the following relations is correct for a basic aqueous solution?

The $pH$ of a water sample collected from a river was found to be acidic in the range of $3.5 - 4.5$. On the banks of the river were several factories that were discharging effluents into the river. The effluents of which one of the following factories is the most likely cause for lowering the $pH$ of river water?

Tooth enamel is the hardest substance in our body. Name the compound of which it is made up. At what $pH$ of the mouth does it get corroded? State the role of bacteria present in the mouth. Suggest a method to prevent tooth decay.