2-7-1
<h3>Further explanation
</h3>
Electrons can move the shell up or down by releasing energy or absorbing energy
Excited electrons show higher electron transfer to the shell by absorbing energy
So it can be concluded that there are 2 conditions:
Ground state is the state of electrons filling shell with the lowest energy levels.
Excited state is the state of electrons which occupies a higher energy level
The state of excited electrons can be seen from the presence of electrons which do not fill the skin completely but fill the skin afterward
2-7-1
From its 8 electron configuration, filling 3 shells, 2 electrons in the firs shell, 7 electrons in the second shell and 1 electron in the third shell
the electrons in the third shell should fill the electrons in the second shell first according to Aufbau rule (lower energy shells)

Answer:
The correct answer is - D. Freezing point depression.
Explanation:
When rock salt is spread over snow-covered icy roads, it generates a liquid layer over it by melting from the surface thereby lowering or depression in the freezing point below the ice.
Therefore, due to this liquid layer comes into the contact with the ice present on the road and causes other ice to melts. This keeps on decreasing the volume of the ice on the road therefore, rock salts spread on the roads during a snowstorm.
the answer is 133
because thats how the water is