Which of the following are singleton sets ?

$\{$ Even numbers which are prime $\}$

State which of the following are null or empty sets?

The set of women army chief in India since $1947$.

State which of the following are null or empty sets ?

$\{$ Men over $300$ years old $\}$

State which of the following are null or empty sets?

The set of odd numbers divisible by $2$.

State which of the following are null or empty sets?

The set of teachers teaching you.

State which of the following are null or empty sets ?

$\{$ Cubes with $8$ faces $\}$

State which of the following are null or empty sets ?

$\{$ Days with $1440$ minutes $\}$

State which of the following are null or empty sets ?

$\{$ Even numbers which are prime $\}$

State which of the following are null or empty sets ?

$\{$ $x|x$ is a person over $100 \mathrm{m}$ tall $\}$