Write the set $\{ x:x$ is a positive integer and ${x^2} < 40\} $ in the roster form.
List all the elements of the following sers :
$E = \{ x:x$ is a month of a year not having $ 31 $ days ${\rm{ }}\} $
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$\{\varnothing\} \subset A$
If $Q = \left\{ {x:x = {1 \over y},\,{\rm{where \,\,}}y \in N} \right\}$, then
Which of the following are sets ? Justify your answer.
A collection of novels written by the writer Munshi Prem Chand.