Step-by-step explanation:
It is known that a solid substance will be made up of atoms which are strongly held together. And, each atom of this solid substance consists of protons, neutrons and electrons.
Only solid substances have a fixed shape and volume.
As electricity is the flow of electrons and a solid substance is able to conduct electricity if it has free electrons available.
For example, in solid state also copper is a good conductor of heat and electricity.
Thus, we can conclude that when a substance is tested in a lab it is found to maintain a unique shape and is a good conductor of electricity if is made up of electron protons and neutrons then state of matter most likely to be solid.