A shape is intangible, it's just an outline or configuration of something else. So it is neither a solid, liquid, or gas... it isn't matter.
However, I do think you mean to say, "Which forms a definite shape: a solid, liquid, or gas?". In this case, only a solid has a definite shape. Liquids and gases take on the shape of its container, which can vary. Solids are the only state of matter that have their own shape, not dependent on a container.
Solid
Superfluidity
These are the three common states of matter. A liquid has a definite volume but takes the shape of its container, a solid has both definite shape and volume, and a gas has neither definite shape nor volume.
sublimation deposition SOLID ============> GAS ==============> SOLID melting freezing SOLID ============> LIQUID =============> SOLID (solidfication) condensation vaporization GAS =============> LIQUID =============> GAS
Marshamallow is a gas and a solid cause it has a shape and it contains many bubbles in it.
Marshamallow is a gas and a solid cause it has a shape and it contains many bubbles in it.
a solid has definite volume and shape, a liquid has definite volume but no shape. a gas has nor volume nor shape
Solids.
Pebbles are solid.
solid melts to liquid and liquid boils to solid
Liquids and gases have no definite shape.
Solid