Consider the sets $\phi, A = \{1, 3\}, B = \{1, 5, 9\}, C = \{1, 3, 5, 7, 9\}$. Insert the symbol $\subset$ or $\not\subset$ between the following pair of sets: $\phi \dots B$.

Write down all the subsets of the following set: $\{a, b\}$

Given the sets $A = \{1, 3, 5\}$,$B = \{2, 4, 6\}$,and $C = \{0, 2, 4, 6, 8\}$,which of the following sets can be considered as a universal set for all the three sets $A$,$B$,and $C$?
$X = \{0, 1, 2, 3, 4, 5, 6\}$

Write the set $A = \{ 1, 4, 9, 16, 25, \dots \}$ in set-builder form.

In set-builder form,the empty set is represented by

Let $A = \{ \theta : \sin(\theta) = \tan(\theta) \}$ and $B = \{ \theta : \cos(\theta) = 1 \}$ be two sets. Then