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

Which of the following sets are finite or infinite.

The set of positive integers greater than $100$

In rule method the null set is represented by

Make correct statements by filling in the symbols $\subset$ or $ \not\subset $ in the blank spaces:

$\{ x:x$ is a circlein the plane $\}  \ldots \{ x:x$ is a circle in thesame plane with radius $1$ unit $\} $

Which of the following are examples of the null set

$\{ x:x$ is a natural numbers, $x\, < \,5$ and $x\, > \,7\} $

State which of the following sets are finite or infinite :

$\{ x:x \in N$ and $x$ is odd $\} $