Why does bleeding stop by rubbing moist alum?

Why does bleeding stops by rubbing moist alum?

In the case of small cuts, bleeding is stopped by applying potash alum. Here alum act as

Why does nose start bleeding on high mountains?

Radha and Meera are fast friends. They both study in class XII. Radha is a student of science while Meera follows commerce stream. One day, when they were playing, Radha got hurt and started Fluiding. Merra took to her house and applied some alum on the cut. The bleeding stopped immediately. (i) Why bleeding stopped when some alum is applied on the cut ? (ii) What are the values associated with Meera's decision to take Radha to her house and apply alum on her cut ?

While learning to ride a bicycle Boojho lost his balance and fell. He got bruises on his knees and it started bleeding. However, the bleeding stopped after some time. (a) Why did the bleeding stop? (b) What would be the colour of the wounded area and why?

It is difficult to stop bleeding from a cut in human body at high altitude. Why?