Answer:
To find the percentage by weight of oxygen in the gaseous compound, we need to first find the weight of the compound that is not oxygen. We can do this by subtracting the weight of the oxygen from the total weight of the compound: 50.0 grams - 30.0 grams = 20.0 grams.
Next, we need to divide the weight of the oxygen by the total weight of the compound and multiply the result by 100% to express the answer as a percentage: 30.0 grams / 50.0 grams * 100% = 60.0%.
Therefore, the percentage by weight of oxygen in the gaseous compound is 60.0%.
Step-by-step explanation: