<h2>
Answer:When electrons absorb or emit quantized units of energy in the form of photons.</h2>
Explanation:
When a electron is collided with a photon with exactly the same energy it would require to get to any of the farther orbits,electron transition takes place to an orbit depending on the energy of the photon.
When electrons emit exactly the same amount energy that is difference between the current energy level and the new level,then the electron makes a transition to the new level.
Opening the valve allows more of the pressurized material out. If the area is decreased, less of the pressurized material is released, and its force ends up more spread out, reducing the pressure. Opening the valve will increase volume of transfer of your liquid.
Space ships.
Hope this helps and have a nice day!!!
Gas has no defined shape or defined volume. Which means that a gas would be able to expand to fill its container.