Question

Which of the following are singleton sets?

$\left\{CapitalofUSA\right\}$

Answer 1

A set containing only one element is called a singleton set.

Given set:

$\left\{CapitalofUSA\right\}$

USA has only one capital which is Washington DC.

Therefore, the set $\left\{CapitalofUSA\right\}$ contains only one element.

Hence, the set of $\left\{CapitalofUSA\right\}$ is a Singleton set.