The excited state which persists for unusually longer period of time is called?

Ground state

Ionized state

Metastable state

Ordinary excited state

Explanation

A metastable state is an excited state of an atom or molecule that has a significantly longer lifetime compared to other excited states, but is still shorter than the ground state.

This means that an electron in a metastable state can stay in that state for a relatively long time before transitioning back to a lower energy level.