Unique
An item or object that is the only one of its kind is referred to as a "unique" or "one-of-a-kind."
A substance that is composed of only one kind of matter is called an element. The smallest particle of an element is called an atom.
Homogenous
A substance that only contains one kind of atom is called an element.
A material made up of only one kind of matter is called a pure substance. It has a uniform composition and specific properties.
Material made up of only one kind of matter is called an Element
The smallest grouping that only contains one kind of organism is called a species. Each species consists of individuals that are capable of interbreeding and producing fertile offspring.
element
Because it is made out of only one kind of element (called neon).
pure substace
well i don't know why the only one is called Development. ---- If the only server you are seeing is one called development, that means the servers are down for maintenance of some kind, be it weekly maintenance or emergency maintenance.
it's called a element according to study island