Which of the following are sets ? Justify your answer.
The collection of all the months of a year beginning with the letter $\mathrm{J}.$
Examine whether the following statements are true or false :
$\{ x:x$ is an even natural number less than $6\} \subset \{ x:x$ is a natural mumber which divide $36\} $
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$\{\varnothing\} \subset A$
Which of the following are examples of the null set
Set of even prime numbers
Write the following intervals in set-builder form :
$\left[ {6,12} \right]$