Which of the following are sets ? Justify your answer.
A team of eleven best-cricket batsmen of the world.
The number of elements in the set $\{x \in R :(|x|-3)|x+4|=6\}$ is equal to
How many elements has $P(A),$ if $A=\varnothing ?$
Let $A, B,$ and $C$ be the sets such that $A \cup B=A \cup C$ and $A \cap B=A \cap C$. Show that $B = C$
Which of the following are examples of the null set
$\{ y:y$ is a point common to any two parallellines $\} $