. Tooth decay starts when the pH of the mouth is lower than


(a)          5.5

(b)          6.5

(c)           7.5

(d)          8.5

 

Best Answer

(a)

Explanation: Tooth enamel made up of calcium phosphate (Ca3PO4) is hardest material in our body. When we eat food containing sugar, then the bacteria present in our mouth break down the sugar to form acid (lactic acid). This acid lowers the pH in the mouth and it is strong enough to attack the enamel of our teeth and corrode it.

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