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

Let $A = \{1, 2, \{3, 4\}, 5\}$. Which of the following statements is incorrect and why?
$1 \subset A$

Examine whether the following statement is true or false:
$\{a, b\} \not\subset \{b, c, a\}$

Let $A = \{1, 2, 3, \ldots, 10\}$ and $B = \left\{\frac{m}{n} : m, n \in A, m < n \text{ and } \gcd(m, n) = 1\right\}$. Then $n(B)$ is equal to:

The number of elements in the set $\{ (a, b) : 2a^2 + 3b^2 = 35, a, b \in Z \} $,where $Z$ is the set of all integers,is

If $A, B$,and $C$ are three sets,then $A \times (B \cup C)$ is equal to