Which of the following are sets ? Justify your answer.

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

Which of the following pairs of sets are equal ? Justify your answer.

$A = \{ \,n:n \in Z$ and ${n^2}\, \le \,4\,\} $ and $B = \{ \,x:x \in R$ and ${x^2} - 3x + 2 = 0\,\} .$

Write the following sets in roster form :

$\mathrm{F} =$ The set of all letters in the word $\mathrm{BETTER}$

List all the elements of the following sers :

$D = \{ x:x$ is a letter in the word $"\mathrm{LOYAL}" $ $\} $

Consider the sets

$\phi, A=\{1,3\}, B=\{1,5,9\}, C=\{1,3,5,7,9\}$

Insert the symbol $\subset$ or $ \not\subset $ between each of the following pair of sets:

$B \ldots \cdot C$

Which of the following are sets ? Justify your answer.

The collection of all boys in your class.