Let $A = \{p, q, r\}$. Which of the following is an equivalence relation on $A$

Let $R$ be a relation from $A = \{2,3,4,5\}$ to $B = \{3,6,7,10\}$ defined by $R = \{(a,b) |$ $a$ divides $b, a \in A, b \in B\}$, then number of elements in $R^{-1}$ will be-

Let $A = \{1, 2, 3\}, B = \{1, 3, 5\}$. If relation $R$ from $A$ to $B$ is given by $R =\{(1, 3), (2, 5), (3, 3)\}$. Then ${R^{ - 1}}$ is

The relation $R =\{( a , b ): \operatorname{gcd}( a , b )=1,2 a \neq b , a , b \in Z \}$ is:

Maximum number of equivalence relations on set $A = \{1, 2, 3, 4\}$ is $N$, then -

Let $R _{1}=\{( a , b ) \in N \times N :| a - b | \leq 13\}$ and $R _{2}=\{( a , b ) \in N \times N :| a - b | \neq 13\} .$ Thenon $N$