What determines a state of matter? Earlier I studied about the three states of matter-gaseous,liquid ans solid. Then, I came to know about Plasma and Bose-Einstein Condensate. Now, scientists are trying to explain superconductivity as a state of matter. But, I would like to know on what factors does scientists rely to decide whether a particular state is a state of matter?  
 A: The wiki article on states of matter should clear up your questions.

In physics, a state of matter is one of the distinct forms that different phases of matter take on. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many other states are known such as Bose–Einstein condensates and neutron-degenerate matter but these only occur in extreme situations such as ultra cold or ultra dense matter. Other states, such as quark-gluon plasmas, are believed to be possible but remain theoretical for now. For a complete list of all exotic states of matter, see the list of states of matter.
Historically, the distinction is made based on qualitative differences in properties. Matter in the solid state maintains a fixed volume and shape, with component particles (atoms, molecules or ions) close together and fixed into place. Matter in the liquid state maintains a fixed volume, but has a variable shape that adapts to fit its container. Its particles are still close together but move freely. Matter in the gaseous state has both variable volume and shape, adapting both to fit its container. Its particles are neither close together nor fixed in place. Matter in the plasma state has variable volume and shape, but as well as neutral atoms, it contains a significant number of ions and electrons, both of which can move around freely. Plasma is the most common form of visible matter in the universe.

Read on in the link provided.
A: Very good Question. The wiki-answer of Main Stream Physics is also already given;
"We have no Idea how define it exactly."  
If you ask; 
What is the viscosity difference between a solid and a liquid ?
You are not going to get any exact answer.  
The same problem goes to Liquid and Gas, though here the Kinetic gas theory provides a good approach to define phase transition in most of the cases. But still ie. the CO2 behaviour in the Surface of Venus is not Gas-alike, but named as a Supercritical fluid.
Reading about plasma is exactly in same problems. So, Plasma is "ionized"? And conducts electricity? Well, the akku of you smartphone has Ionised-matter, and for the elctricity-conduction is mostly used solid matters.
So, You have Either accept this Main-Stream answer, "No idea?", or open your eyes and Start to search the true answer.
I have found an answer, which is based on the speed of light, and the quantum-mechanical interactions, which is timed through the speed of light.
The background is explained in this paper of mine, named; States of matter defined from the speed of light. Where the following Statements are supported by the observations and calculations. 
THE ANSWER to your question is thus; 


*

*The Matter must be compressed in pressure and temperature, which forces the molecule to a space less than 1/c [m] to force it to Condensated Matter.  

*The Molecular density must be compressed below pressure and temperature, which forces the molecule to have less than 1/c [s] mean-free-path to force it to form tensionless Kinetic Matter.  

*The Molecular density must be compressed below pressure and temperature, which forces the molecule to have less than   [s] mean-free-path to force it to form a Grounded Matter  free of permanent Electric potential differences.  

*Matter which doesn’t have the required pressure and Temperature remains permanently charge carrying Electric Matter. 
