CHEMISTRY PLEASE HELP!!!

1 and 3 only

Explanation:

When a reaction is equilibrium, its forward reaction and reverse reaction are happening at the same rate. For a reaction to have a forward reaction and reverse reaction, the reaction must be reversible. Therefore, statement #2 is incorrect. Now, since the forward reaction and reverse reaction are moving at the same rate, the rate at which products are being converted to reactants is equal to the rate at which reactants are being converted to products. This means the concentrations of the reactants and products stay constant. That means statement #3 is correct. For equilibrium to happen, the system must be closed though. If a system is closed, that means no hydrogen, iodine, or hydrogen iodide can escape the system. Therefore, statement #1 is also incorrect.