The collection of intelligent students in a class is:

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 pair of sets: $A, \ldots B$.

Consider the experiment of rolling a die. Let $A$ be the event 'getting a prime number' and $B$ be the event 'getting an odd number'. Write the sets representing the events $A$ and $B$.

The number of subgroups of the group $(Z_{5}, +_{5})$ is

Determine the subset for the set $\{n(n+1)(2n+1) : n \in \mathbb{Z}\}$.

Find sets $A, B$ and $C$ such that $A \cap B, B \cap C$ and $A \cap C$ are non-empty sets and $A \cap B \cap C = \varnothing$.