Write the following intervals in set-builder form :

$\left( { - 3,0} \right)$

Write the following sets in the set-builder form :

$\{ 2,4,6 \ldots \} $

In each of the following, determine whether the statement is true or false. If it is true, prove it. If it is false, give an example.

If $A \subset B$ and $B \subset C,$ then $A \subset C$

What universal set $(s)$ would you propose for each of the following :

The set of right triangles

Which of the following are examples of the null set

Set of odd natural numbers divisible by $2$

Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?

$1 \in A$