The number of non-empty subsets of the set $\{1, 2, 3, 4\}$ is

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:

$A, \ldots B$

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

$\{\varnothing\} \subset A$

Examine whether the following statements are true or false :

$\{ 1,2,3\}  \subset \{ 1,3,5\} $

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.

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