State which of the following sets are finite or infinite :

$\{ x:x \in N$ and $2x - 1 = 0\} $

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

$1 \subset A$

Examine whether the following statements are true or false :

$\{ a,b\}  \not\subset \{ b,c,a\} $

Write the following sets in the set-builder form :

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

In the following state whether $\mathrm{A = B}$ or not :

$A = \{ x:x$ is a multiple of $10\} ;B = \{ 10,15,20,25,30 \ldots  \ldots \} $

Show that the set of letters needed to spell $"\mathrm{CATARACT}"$ and the set of letters needed to spell $"\mathrm{TRACT}"$ are equal.