How do you know when a chemical reaction has taken place?

The difference between the atomic number of an element and the element’s atomic mass is the number of ions.

Consider the reaction: n2(g) + o2(g) ? 2no(g) kc = 0.10 at 2000oc starting with initial concentrations of 0.040 mol/l of n2 and 0.040 mol/l of o2, calculate the equilibrium concentration of no in mol/l how would this be done?

Answer asap need by wednesday morning calculate the ph of 0.16m ch3cooh which has ka = 1.74 x 10-5 mol dm-3 best answer will be brainliest