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

Make correct statements by filling in the symbols $\subset$ or $\not\subset$ in the blank spaces:
${ x:x \text{ is an equilateral triangle in a plane} } \dots { x:x \text{ is a triangle in the same plane} }$

In the following,state whether $A=B$ or not:
$A=\{4, 8, 12, 16\}; B=\{8, 4, 16, 18\}$

Let $S = \{0, 1, 5, 4, 7\}$. Then the number of all subsets of $S$ is:

If $A \subseteq B$,then $A \cap B$ is equal to

Make correct statements by filling in the symbols $\subset$ or $\not\subset$ in the blank spaces:
$\{a, b, c\} \dots \{b, c, d\}$