Final answer:
The total pressure of a gas mixture containing oxygen, nitrogen, and hydrogen is the sum of the partial pressures of each gas. Therefore, by adding 300 mmHg (oxygen), 400 mmHg (nitrogen), and 200 mmHg (hydrogen), we get a total pressure of 900 mmHg.
Step-by-step explanation:
The total pressure of a gas mixture containing 300 mmHg of oxygen, 400 mmHg of nitrogen, and 200 mmHg of hydrogen can be found by simply adding the partial pressures of the individual gases together.
According to Dalton's Law of Partial Pressures, the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of individual gases.
Therefore, the total pressure of the gas mixture is:
PTotal = Pressure of Oxygen + Pressure of Nitrogen + Pressure of Hydrogen
PTotal = 300 mmHg (Oxygen) + 400 mmHg (Nitrogen) + 200 mmHg (Hydrogen)
PTotal = 900 mmHg
Thus, the total pressure of the gas mixture is 900 mmHg.