Answer
There are 50 electron states in a shell defined by the quantum number $n = 5$
Work Step by Step
On page 1225, the text states: "If we count all the states throughout a given shell with quantum number $n$, we find that the total number in the shell is $2n^2$"
We can find the number of electron states in the $n=5$ shell:
$2n^2 = (2)(5)^2 = 50$
There are 50 electron states in a shell defined by the quantum number $n = 5$
