Answer:
A solution is a homogeneous mixture of two or more substances. The particles of solute in a solution cannot be seen by the naked eye. A solution does not allow beams of light to scatter.
Explanation:
The answer is: when the aim is to show electron distributions in shells
An orbital notation is more appropriate if you want to show how the electrons of an atom are distributed in each subshell. This is because there are some atoms that have special electronic configurations that aren't obvious in just written configurations.
The swimming pools pH is below 7, meaning it is slightly acidic. If you want to make the pH higher, you must add a base which by definition has a pH higher than 7.
D. Add base