To improve air quality and obtain a useful product, chemists often remove sulfur from coal and natural gas by treating the contaminant hydrogen sulfide with O2: 2H2S(g) + O2(g) = 2S(s) + 2H2O(g)

What happens to

a) [H2O] if O2 is added?

b) [H2S] if O2 is added?

c) [O2] if H2S is removed?

d) [H2S] if sulfur is added?

1) Increase

2) Decreases

3) increases

4) Increase

Explanation:

These questions can only be answered by considering the principle which states that, "When a constraint such as a change in concentration, pressure or volume is imposed on a reaction system in equilibrium. The system will readjust itself in order to annul the constraint."  

Now, if more reactants are added, the equilibrium position will shift towards the right, If more products are added, the equilibrium position will shift to the left.

Similarly, the removal of H2S causes the O2 concentration to increase since the equilibrium position now shifts to the left.

Also, addition of O2 causes H2S to be removed as the equilibrium moves to the right.

it means there are 3 atoms of oxygen