Question

‌What‌ ‌is‌ ‌$pH$‌ ‌scale?‌ ‌Explain‌ ‌that‌ ‌$pH$‌ ‌change‌ ‌of‌ ‌mouth‌ ‌is‌ ‌the‌ ‌cause‌ ‌of‌ ‌tooth‌ ‌decay.‌ ‌

Answer 1

-The concentration of proton is a measure of acidity of a substance, meaning, higher the concentration of proton in a solution, more acidic the solution will be.
-Theoretically, the concentration of these protons can be measured by writing the equilibrium equation, but the practical and more viable approach to measure the acidity of a solution is also important.

Complete answer: $pH$ can be defined as the negative log of ${{H}^{+}}$ ion or the proton concentration present in the solution. Hence the literal meaning of the name $pH$ is usually justified as the power of hydrogen.A $pH$ scale is a kind of tool which is used for measuring the content of acids and bases. The $pH$ scale ranges from $0-14$, $0$ being the most acidic and $14$ being the most basic. Litmus paper is the most commonly used indicator which is used to tell if a chemical is acidic or basic. The colour indicated by the litmus paper is matched with the numbers provided on the $pH$ scale in order to indicate the nature of the substance which is being tested. For instance, Vinegar is a weak acid and on the $pH$ scale it measures $2.4$.A glass electrode along with $pH$ metre, or an indicator which tends to change colour, could be used to measure the extent of the $pH$ of aqueous solutions.Inside the mouth of a human being if the $pH$ of the mouth decreases because of consumption of certain kinds of food with acidic content, and isn’t washed in time, causes tooth decay. This is because the tooth has calcium content, and it reacts with the acid being formed in the mouth.

Note: -The $pH$ of a solution is the measure of the concentration of protons present in the solution. If the concentration of ${{H}^{+}}$ is more than the $pH$ will be less and vice versa.
-There are certain food elements which provokes the $pH$ of the mouth to go down, in other words, they make the $pH$ of the mouth acidic, which causes tooth decay, as the tooth are made up of calcium, which reacts with the acid present in mouth.