Let $A = \{1, 2, 3, 4, 5, 6\}$. Insert the appropriate symbol $\in$ or $\notin$ in the blank space:
$10 \dots A$

Examine whether the following statement is true or false:
$\{a, e\} \subset \{x : x \text{ is a vowel in the English alphabet}\}$

Examine whether the following statement is true or false:
$\{x : x \text{ is an even natural number less than } 6\} \subset \{x : x \text{ is a natural number which divides } 36\}$

The number of proper subsets of the set $\{1, 2, 3\}$ is

Which of the following is an empty set?

State whether the following statement is true or false. Justify your answer.
${2, 6, 10}$ and ${3, 7, 11}$ are disjoint sets.