Which of the following are sets ? Justify your answer.
The collection of all the months of a year beginning with the letter $\mathrm{J}.$
Write the following sets in the set-builder form :
$\{ 1,4,9 \ldots 100\} $
State whether each of the following set is finite or infinite :
The set of letters in the English alphabet
State which of the following sets are finite or infinite :
$\{ x:x \in N$ and $2x - 1 = 0\} $
In the following state whether $A=B$ or not :
$A=\{a, b, c, d\} ; B=\{d, c, b, a\}$