List all the elements of the following sers :
$C = \{ x:x$ is an integer ${\rm{; }}{x^2} \le 4\} $
$C = \{ x:x{\rm{ }}$ is an integer ${\rm{ }};{x^2} \le 4\} $
It can be seen that
${( - 1)^2} = 1\, \le \,4;{( - 2)^2} = 4\, \le \,4;{( - 3)^2} = 9\, > \,4$
$0^{2}=0 \leq 4$
$1^{2}=1 \leq 4$
$2^{2}=4 \leq 4$
$3^{2}=9>4$
$\therefore C=\{-2,-1,0,1,2\}$
Which of the following are sets ? Justify your answer.
The collection of all natural numbers less than $100 .$
Given the sets $A=\{1,3,5\}, B=\{2,4,6\}$ and $C=\{0,2,4,6,8\},$ which of the following may be considered as universal set $(s)$ for all the three sets $A$, $B$ and $C$
$\varnothing$
State whether each of the following set is finite or infinite :
The set of letters in the English alphabet
Let $S=\{1,2,3, \ldots, 40)$ and let $A$ be a subset of $S$ such that no two elements in $A$ have their sum divisible by 5 . What is the maximum number of elements possible in $A$ ?
The number of non-empty subsets of the set $\{1, 2, 3, 4\}$ is