State which of the following sets are finite or infinite:
$\{ x:x \in N \text{ and } x^2 = 4 \}$

The dual of $(x+y) \cdot (x^{\prime} \cdot 1)$ is:

How many elements does $P(A)$ have,if $A = \varnothing$?

In this question,all integers are represented in base $10$. Consider the set $E$ of positive integers $n$ having the property that when any nonzero digit $d \in \{1, 2, \dots, 9\}$ is written to the right of $n$,the resulting number is divisible by $d$. Let $N$ be the smallest element of $E$. The product of the digits of $N$ is:

State whether the following statement is true or false. Justify your answer.
${2, 6, 10}$ and ${3, 7, 11}$ are disjoint sets.

Which of the following is a set? Justify your answer.
The collection of all the months of a year beginning with the letter $J$.