Which convenient category is used for the classification of organisms?

In biological nomenclature,which name of an organism,once used,cannot be used for the naming of any other organism?

Complete the following table regarding Mango $(Mangifera \text{ } indica)$:

Kingdom	Plantae
Division	$P$
Class	Dicotyledonae
$Q$	Sapindales
$R$	Anacardiaceae

$P \quad \quad \quad \quad Q \quad \quad \quad \quad R$

In which order is the human placed?

$Order$ is the assemblage of families which exhibit a few similar characters.

Dicotyledonae is a ....... .