Which of the following are examples of the null set

Set of odd natural numbers divisible by $2$

Make correct statements by filling in the symbols $\subset$ or $ \not\subset $ in the blank spaces:

$\{a, b, c\} \ldots\{b, c, d\}$

Let $A=\{a, e, i, o, u\}$ and $B=\{a, i, u\} .$ Show that $A \cup B=A$

State whether each of the following set is finite or infinite :

The set of animals living on the earth

In the following state whether $\mathrm{A = B}$ or not :

$A = \{ 2,4,6,8,10\} ;B = \{ x:x$ is positiveeven integer and $x\, \le \,10\} $

In the following state whether $A=B$ or not :

$A=\{4,8,12,16\} ; B=\{8,4,16,18\}$