Why injury to cartilage takes a long time to heal?

A milkman adds a very small amount of baking soda to fresh milk. Why does this milk take a long time to set as curd?

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?

If a drop of water falls on a very hot irion, it takes long time to evaporate. Explain why?