Who discovered the 4th state of matter plasma?

Answer 1

Plasma was first identified in a Crookes tube, and so described by Sir William Crookes in 1879 (he called it "radiant matter")

.The nature of the Crookes tube "cathode ray" matter was subsequently identified by British physicist Sir J.J. Thomson in 1897.The term "plasma" was coined by Irving Langmuir in 1928,perhaps because the glowing discharge molds itself to the shape of the Crooks tube (a thing moulded or formed).Langmuir described his observations as:

Except near the electrodes, where there are sheaths containing very few electrons, the ionized gas contains ions and electrons in about equal numbers so that the resultant space charge is very small. We shall use the name plasma to describe this region containing balanced charges of ions and electrons.