(a) Write the nam

(a) Water soluble bases are called alkalis, e.g., NaOH, KOH.

(b) Tooth decay starts when the pH of the mouth is lower than 5.5. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. This can be prevented by cleaning the mouth and teeth using toothpastes which are generally basic and can neutralize the excess acid.

(c) When a honeybee stings a person, it injects an acidic liquid into the skin which causes immense pain and irritation. Rubbing a mild base like baking soda solution on the stung area of the skin gives relief. This is because, being a base, baking soda neutralises the acidic liquid injected by bee sting and cancels its effect.