Which of the following are sets ? Justify your answer.

A team of eleven best-cricket batsmen of the world.

Write the following sets in the set-builder form :

$\{ 2,4,6 \ldots \} $

Which of the following sets are finite or infinite.

The set of prime numbers less than $99$

Write the following sets in the set-builder form :

$\{ 3,6,9,12\}$

Which of the following sets are finite or infinite.

$\{1,2,3 \ldots .\}$