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

$\{ x:x$ is a triangle in a plane $\}  \ldots \{ x:x$ is a rectangle in the plane $\} $

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 $A \subset C$

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 $x \notin B,$ then $x \notin A$

List all the elements of the following sers :

$F = \{ x:x$ is a consonant in the Englishalphabet which precedes $k\} $

Write the following sets in the set-builder form :

$\{ 1,4,9 \ldots 100\} $

In rule method the null set is represented by