Why must the physical state of reactants and products be stated in a thermochemical reaction?

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

0.2348 grams of pbcl2 used to form 44.0 ml of solution.

How many moles of gas are present if p=11 atm, v=12l, t=185k?