First, let's write the balanced equation for the formation of water from hydrogen and oxygen.
This equation indicates that two parts of H2 and one part of O2 are needed to form every two parts of H2O.
For simplicity, let's also label the columns in the table from left to right as A through G.
In column A, zero oxygen is present, thus no water can form.
In B, we begin with 5 parts of H2 and end with 3, indicating that 2 parts were consumed in the reaction along with 1 part of oxygen. We can see from the balanced equation that two H2 and one O2 combined to yield two parts of water.
In C, we begin with 4 parts of H2 and 2 parts of O2. Neither reactant is present in excess (this means both were fully consumed in the reaction). This is twice the material as in B, thus 4 parts of water formed.
In D, we begin with 3 parts of H2 and O2, and have 1.5 parts of O2 left over, indicating 3 parts of water formed.
In E, we begin with 2 of H2 and 4 of O2. At the end, 3 of O2 remain. This indicates that 1 part O2 was consumed, along with the 2 parts H2, yielding 2 parts water.
In F, we begin with 1 part H2 and 5 parts O2. At the end, 4.5 parts of O2 remain, indicating 0.5 parts O2 were consumed, along with the 1 part H2, resulting in 1 part H2O.
In column G, zero hydrogen is present, thus no water can form.