Write down all the subsets of the following sets

$\emptyset $

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

$\{1,2,3\}\subset A$

Which of the following are sets ? Justify your answer.

The collection of all the months of a year beginning with the letter $\mathrm{J}.$

Let $A=\{1,2,3,4,5,6\} .$ Insert the appropriate symbol $\in$ or $\notin$ in the blank spaces:

$ 0\, ........\, A $

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

$\{ y:y$ is a point common to any two parallellines $\} $