Match the three phases of matter.
1. fixed volume; variable shape gas
2. fixed volume; fixed shape liquid
3. variable volume; variable shape solid

Matter is defined as anything which has volume and mass. Three phases of matter: Solid, liquid and gas.

Solid: The substances in which particles are closely packed, has definite volume and definite shape.

Liquid: Particles are loosely packed as comparison to solid, has definite volume and take the shape of container i.e. indefinite shape.

Gas: Particles are loosely packed, has indefinite volume and indefinite shape.

Thus,  gas: variable volume; variable shape

liquid: fixed volume; variable shape    

solid: fixed volume; fixed shape

if the concentration of products is decreased, the equilibrium will shift toward the products). add an inert gas (one that is not involved in the reaction) to the constant-volume reaction mixture: this will increase the total pressure of the system, but will have no effect on the equilibrium condition.

explanation: