State whether the following set is finite or infinite:
The set of letters in the English alphabet.

Which of the following pairs of sets are disjoint?
$A = \{ x : x \text{ is an even integer} \}$
$B = \{ x : x \text{ is an odd integer} \}$

Which of the following are sets? Justify your answer.
$A$ collection of the most dangerous animals of the world.

If $A = \{x \in R : x^2 - 5|x| + 6 = 0\}$,then find $n(A)$.

Let $A$ and $B$ be two sets. Then

State which of the following sets are finite or infinite:
$A = \{ x : x \in \mathbb{N} \text{ and } x \text{ is prime} \}$