Question

The pH value of the saliva before meal is ____________and after meal is ______________.
A . $5,7.4$
B . $7,10$
C . $7.4,5.8$
D . 2,5

Answer 1

Hint : The normal pH range of the saliva is $6.2$ to $7.6$. Meal changes the pH level of saliva. This is because there are so many bacteria in our mouth, when we eat any food or drink something bacterias breaks down the carbohydrate that we consume and releases lactic acid, butyric acid and aspartic acid which changes the pH level of our mouth.

Complete answer:
> So the pH value of the saliva before the meal is $7.4$ and after the meal is $5.8$. Here option C is correct, that is $7.4,5.8$ . The pH value indicates that before taking the meal saliva remains slightly basic but after taking meals it becomes acidic .

 Additional information -The change in pH value of saliva has a play role in ages as adults tend to have more acidic saliva than children. We should always try to balance the pH level of our mouth as it is necessary for our health. When we drink any acidic beverages , the pH level of saliva can be dropped below $5.5$ then this acid starts to break down tooth enamel . Symptoms of unbalanced saliva are sensitivity to hot or cold food or beverages , tooth cavities and persistent bad breath.

Note : Before eating meal pH of the mouth remains at $7.4$ which is equal to the pH of blood .But when we take our meal the pH of the saliva changes to $5.8$.This happens because of the increase in the activity of bacteria which increases acidity of the saliva as it break down the carbohydrates in various acids such as lactic acetic and butyric acid etc.