Solution: There are major three phases of substance, namely solid, liquid and gas.
Here, solid substances have definite shape, they are rigid and can not change their volume or shape if kept in any container.
Liquid substances do not have any shape of their own, they take shape of the container in which they are kept. They are compressible in nature.
Gaseous substances also do not have their own shape, the molecules of gas continuously move in the container in which they are stored. Gases are highly compressible in nature.
Here, a substance when placed in a 100-mL square box have spherical shape and 50 mL volume. The shape and volume of the substance do not change when it is placed in a 100-mL circular tube, that means it does not change the shape with change of container and the state of substance will be solid.