Which of the following are examples of the null set
$\{ y:y$ is a point common to any two parallellines $\} $
List all the subsets of the set $\{-1,0,1\}.$
Write the set $\{ x:x$ is a positive integer and ${x^2} < 40\} $ in the roster form.
Write the following sets in roster form :
$B = \{ x:x$ is a natural number less than ${\rm{ }}6\} $
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:
$A, \ldots B$