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

If $A = \{1, 2, 3, 4, \dots, 10\}$, then the number of non-empty subsets of $A$ containing only even numbers is

Given the sets $A = \{1, 3, 5\}$,$B = \{2, 4, 6\}$,and $C = \{0, 2, 4, 6, 8\}$,which of the following sets can be considered as a universal set for all the three sets $A$,$B$,and $C$?
$X = \{0, 1, 2, 3, 4, 5, 6\}$

In a city,no two persons have an identical set of teeth,and there is no person without a tooth. Also,no person has more than $32$ teeth. If we disregard the shape and size of the teeth and consider only the presence or absence of a tooth at each of the $32$ positions,then the maximum population of the city is:

List all the elements of the following set:
$E = \{ x : x \text{ is a month of a year not having } 31 \text{ days} \}$

Which of the following is a set? Justify your answer.
The collection of all the months of a year beginning with the letter $J$.