Home › Tamil Nadu SSLC (Class 10) › Chemistry › Types of Chemical Reactions › When the pH of mouth saliva falls below 5.5, the…
When the pH of mouth saliva falls below 5.5, the enamel of teeth gets weathered. Why are toothpastes used to counter this?
AThey are acidic and add more acid to saliva
BThey are basic and increase the acid level
CThey are neutral and dilute the saliva fully
DThey are basic and neutralise the excess acid
Answer & Solution
Correct answer: D. They are basic and neutralise the excess acid
1. Tooth decay begins when excess acid lowers the mouth pH below 5.5, attacking the enamel.
2. Toothpastes are generally basic.
3. A base neutralises acid, so the basic toothpaste cancels the excess acid; an acidic paste would worsen decay.
4. Therefore toothpastes are basic and neutralise the excess acid.
_Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 10 Types of Chemical Reactions "Role of pH in Everyday Life", p.156_
Related questions
If a solution has a pOH of 11.76 at 25 degrees Celsius, what is its pH?What is the pH of a 1 x 10^-4 molar solution of sodium hydroxide, a strong base, at 25 degWhat is the pH of a sulphuric acid solution that is 5 x 10^-5 mol per litre in concentratiWhat is the pH of a 0.01 M solution of nitric acid (HNO3), a strong monobasic acid?On the pH scale, a solution with a pH greater than 7 is correctly described as:At 25 degrees Celsius the ionic product of water Kw equals the product of which two concenA catalyst changes a reaction in which specific way?Powdered calcium carbonate reacts faster with hydrochloric acid than marble chips of the s