Asubstance with a definite shape and volume is a phase of matter.

Solid

Explanation:

As we know that there are 3 states of matter :

Solid state : It is a state in which the particles are closely packed and does not have any space between them. This state has a definite shape and volume.

Liquid state : It is a state in which the particles are present in random and irregular pattern. The particles are closely arranged but they can move from one place to another. This state has a definite volume but does not have a fixed shape.

Gaseous state : It is a state in which the particles are loosely arranged and have a lot of space between them. This state has indefinite volume as well as shape.

there all right good

explanation:

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.