Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$1 \in A$
Which of the following are examples of the null set
Set of odd natural numbers divisible by $2$
Are the following pair of sets equal ? Give reasons.
$A = \{ 2,3\} ,\quad \,\,\,B = \{ x:x$ is solution of ${x^2} + 5x + 6 = 0\} $
Write the following sets in the set-builder form :
${\rm{\{ 5,25,125,625\} }}$
List all the elements of the following sers :
$E = \{ x:x$ is a month of a year not having $ 31 $ days ${\rm{ }}\} $