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

Two sets $A$ and $B$ are disjoint if and only if

Write the following set in roster form:
$A = \{ x : x \text{ is an integer and } -3 < x < 7 \}$

In each of the following,determine whether the statement is true or false. If it is true,prove it. If it is false,give an example.
If $A \subset B$ and $B \subset C$,then $A \subset C$.

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

If $A = \{2, 3, 4, 5, 6\}$,then which of the following statements has a truth value of 'false'?