Why does tooth decay start when the pH of mouth is lower than 5.5?

Tooth decay start when the pH of the mouth is lower than-

Assertion (A) : Tooth decay starts when the pH of the mouth is lower than 5.5. Reason : Bacteria present in mouth produce bases.

When does tooth decay start in our mouth ?

Why does smoke like vapour come out of our mouth in winter?

When does the heart beat start in the human embryo?

Why does the dough rise when yeast is added to it?

A milkman adds a very small amount of baking soda to fresh milk. Why does he shift the pH of the fresh milk from 6 to slightly alkaline

Why does the car with a flattened tyre stop sooner than the one with inflated tyres ?

A milkman adds a very small amount of baking soda to fresh milk. (a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline? (b) Why does this milk take a long time to set as curd?