Question

What if we put a part of our hand in vacuum chamber? Will it burst or remain as it is.... Or something else?

Answer 1

You’re going to feel a painful swelling in your arm, and a good number of capillaries/blood vessels close to the surface will probably burst, which will make your arm look pretty nasty. If you have an open wound anywhere on your arm, the pressure difference might cause you to bleed more severely, but blood is viscous enough that I doubt it would spray out like a fountain. (I admit that I’m not sure about that one.)

Due to the decreased pressure, moisture on your skin will rapidly boil away, causing your skin to become very dry. Pockets of water vapor will form in your blood vessels, effectively blocking circulation. If you leave your arm exposed for several minutes, tissue will start to die off. Even if you retract your arm to a pressurized environment, the prolonged loss of circulation might cause gangrene. You might wind up losing your arm after all during a life-saving amputation.