Question

hair of shaving brush spreads out when dipped in h2o an sticks out when taken out. small mercury drops are sperical while bigger ones tends to expand. olive oil spreads on cold h2o bt reman as drop in hot h2o.

Answer 1

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1-
When a dry shaving brush is dipped into water,its hair spread out. But when it is taken out of the water,its hair are pressed together. It is so because a thin water film is formed at the tips of the hair which contract due to surface tension and presses the hair.