On absorbing energy, an electron moves to an excited state (unstable state) from its ground state (stable state). Since the electron is in unstable state so it tends to rearrange itself to return to its lowest energy state. On returning to lowest energy state which is stable, it releases energy in the form of light.
Hence, option A that is the electron releases energy in the form of light on falling to lower energy state from excite state.
<h2> The correct option is (a).</h2>
Explanation:
- There is no change of state in pouring water into a vacuum insulated bottle as the vacuum created inside the bottle only reduces the time limit for the transfer of heat by conduction and convection.
- It helps the content filled in the bottle to be hot and cool for a longer time.
Hence, option (a) is correct.
Rest of the options (b), (c), (d), (e) is not correct because of the following reasons:
- In the sublimation of dry ice, the dry ice (solid-state) is changed to the vapour form.
- In the freezing of water, the liquid state is changed to solid-state.
- During the vaporization of alcohol, the liquid state is changed to the vapour form.
- During the melting of ice, the solid-state is changed to the liquid state.
