Write down all the subsets of the following sets

$\{ a,b\} $

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 $A \not\subset B$ and $B \not\subset C,$ then $A \not\subset C$

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 each of the following pair of sets:

$B \ldots \cdot C$

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

$1 \subset A$

Which of the following sets are finite or infinite.

$\{1,2,3, \ldots 99,100\}$

Which of the following sets are finite or infinite.

The set of months of a year