What is the importnace of every reaction opposite reaction

Kc = 0.040 for the system below at 450oc. if a reaction is initiated with 0.40 mole of cl2 and 0.40 mole of pcl3 in a 2.0 liter container, what is the equilibrium concentration of cl2 in the same system? pcl5(g) ⇄ pcl3(g) + cl2(g)

In the experiment you asked to react hydrochloric acid and with sodium hydroxide. when measuring the volume of the reactants, which instrument would give the greatest precision.

Give 2 characteristics of low mass stars