Write the following sets in roster form :
$C = \{ x:x{\rm{ }}$ is a two-digit natural number such that sum of its digits is $8\} $
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$\{ 3,4\} \subset A$
State which of the following sets are finite or infinite :
$\{ x:x \in N$ and $x$ is odd $\} $
Which of the following are sets ? Justify your answer.
The collection of all even integers.
Write the set $A = \{ 1,4,9,16,25, \ldots .\} $ in set-builder form.