Find the union of each of the following pairs of sets :

$A=\{1,2,3\}, B=\varnothing$ 

Let $A$ and $B$ be two sets in the universal set. Then $A – B$ equals

If $n(A) = 3$, $n(B) = 6$ and $A \subseteq B$. Then the number of elements in $A \cup B$ is equal to

If $A=\{3,5,7,9,11\}, B=\{7,9,11,13\}, C=\{11,13,15\}$ and $D=\{15,17\} ;$ find

$A \cap C$

If $A=\{x \in R:|x|<2\}$ and $B=\{x \in R:|x-2| \geq 3\}$ then