Answer:
yup that's how you make friends with people on brainly
It should be B. All of the other choices are used often by abusers
For the chemical reactiom to be at equilibrium:
1- The rate of forward reaction must be equal to the rate of the reverse reaction.
2- The mass of EACH element must be equal before and after the reaction (no NET change in mass), otherwise the equilibrium will shift.
Important note: you need to check the mass of each element before and after the reaction (i.e, reactants side and products side) and the not the mass of the system as a whole. This is because the mass of the whole system will be preserved whether the system is at equilibrium or not (this is the fundamental law of mass conservation)