We know according to Le Chatelier's principle or "The Equilibrium Law" states that when a system experiences a disturbance (such as concentration, temperature, or pressure changes), it will respond to restore a new equilibrium state.
In this case rate of production of decreases when:
1. When concentration of HCl decreases.
2. When concentration of either or increases.
3. Increase in temperature because it is exothermic reaction.
A. Oxygen. Oxygen has an atomic mass of 16. The atomic mass of an atom is the combined weight o the protons and neutrons. Since Oxygen's atomic mass is 16, it has 8 protons and 8 neutrons.