Answer
a) no
b) no
c) yes
d) yes
e) yes
f) no
Work Step by Step
a and b) This is a set of integers. Since none of the elements of the set are sets, $\{2\}$ cannot be an element.
c-e) $\{2\}$ is listed in the elements of each of these sets
f) Although $\{\{2\}\}$ is an element, this is not the same as $\{2\}$. So $\{2\}$ is not an element of the set.
