In the following state whether $A=B$ or not :

$A=\{a, b, c, d\} ; B=\{d, c, b, a\}$

Write the following sets in roster form :

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

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

$\{1,2,3\}\subset A$

Write down all the subsets of the following sets

$\{ a\} $

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

$\{ 3,4\}  \subset A$

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:

$\phi \,....\,B$